Hello Eevvee, thanks very much for posting you're situation. Its good to hear that you're adament about looking for help. This is a great place to ask, and learn and catch yourself doing and thinking a great many things. People relate to everything you say, think, and feel... Just remember - no matter how strange and alone you feel - really come to realize that, "YOU ARE NOT ALONE," and that there ARE people out there - whom understand what you are going through. Often times words are not enough to describe what (I'm assuming) - you are experiencing... It takes alot of guts to come on here anonymously and spill everything out into paragraphs.
Know that people on here read, "beyond," the words - and try their best to get to the, "core," of your issues; and why you are / may be; experiencing these, "symptoms..." I hope to offer you some help. If not; just know that we are always here to listen.

We read, "between," the lines - emotions run deep in words - subtext is the only way we can, "breath," the air you breath. "See," the things that you see... We all experience different things, as similar as they may seem. We are all similar - in that we all have a heart. I hope to help you out.
Anyways - enough of that babbling metaphorical nonsense. Back to the serious topics.
Sounds to me - like you're experiencing the full gamut of mental illness. It isn't easy to determine what you have, but you CAN look into, "WHY," you may be experiencing the things you claim to be experiencing... You've basically - listed off; everything that accompanies the majority of mental illness. For sure - you've been put through a difficult time, only expect things to get worse - IF; you should decide, NOT to seek help.
If you want help on here - I have a few basic questions I'd like to ask you. In order to help you in the ways we can on healthboards - we'll need alittle more insight into your past and your emotions... I'm NOT forcing these questions on you. These are just questions that I have for you - it would help if you could answer these to the best detail you can muster. I know talking on forums seems like a waste of time - BUT; it CAN, and IS; a rewarding experience if you're willing to bring something to the table. Please continue sharing your personal history / experiences with us.
I got a question for you...
"Have you experienced a severe trauma in your life?" You ARE experiencing these thing YES... ACCEPT that you are - and move past denial... In order to get better - first you gotta ACCEPT that you are in FACT; experiencing these symptoms. Once you've done that - you can start to question, "WHY," you are experiencing these things. No one can do this for you - but you should take it seriously. Reason why... "Why wouldn't you!?"
Another question...
You claim that its extremely hard to be in public places, to, "function," normally in everyday situations and circumstances - that unfortunately are unavoidable in today's societies. Did you always feel this way? If not - at what point / age; did things start to get, "unbearable," where you became uncomfortable doing things that you may have / would have; been able to do easily before? (BASICALLY - was there a point in
time; when things suddenly got worse for you? A time - that even today; stands out in your mind?)
Another question...
You claim to be experiencing, "Physical pain," all the time... Are you referring to the headaches? Or the, "pressure," that you've referred to have been experiencing?
Another question...
Are you taking medications? Have you been diagnosed? Have you seen psychiatrists? Have you told anyone? (I assume you've told your sister a few things - one; you mentioned that you think people's nose's are funny... I'm assuming because of this - your sister has caught onto the way you think)
Another question...
Have you ever done drugs? Are you addicted to alcohol? Have you ever been physically abused? Emotional Abused? Verbally abused? Any trauma that you remember having extremely deep emotions expell out of you?
Another question...
You say, "I feel like my life is over... I'm only 18..." Given that you feel that way... Do you periodically; with, and or; without REASON - feel the opposite from time to time? You feel DOWN occasionally... (Thats normal) Do you ever feel really UP? I'm not talking about happiness... There is no limit to how happy you should feel, EVER... But there is a certain extent of, "HIGH," that you should only ever experience while on drugs... Have you ever had moments of, "CLARITY," where everything seems to make perfect sense... As if nothing can touch you? That you are unstoppable - extremely motivated, extremely inspired? IF SO - what do you usually do about these positive feelings?
Another question...
Have you ever felt suicidal? If so - when? Was it early on in your life? Was it recently? Please explain.
One thing I feel the need to tell you... You (Several times) said that you can't talk, "normally..." That you can't, act, "normally..." That you can't, blink, "normally..." Do you constantly think in terms of whats IS normal and what ISNT normal? Does it keep you from living life, to the, "fullest?"
I ask - because; it sounds like you're being controlled by these thoughts... If you're constantly, "thinking," and it controls the way in which you act in life. If you are fearful because you WANT or DONT WANT - to be, "normal..." Then that could be a debilitating thing on its own. And anxiety could be there for a reason... Which is why I'm asking you to look at the reason(s); as to, "WHY," you may be experiencing these symptoms... Because ultimately - if you can find the answer as to WHY - you could then - and only then - potentially start fixing those things; and prevent any further distress like what you are experiencing now.
As far as you feeling thankful for your boyfriend - thats a good thing. If thats what it takes to keep you
grounded (Even if and when; you do yell at him for reasons that may / may not be; regarded - plausible) that is a great stepping stone. And often times - when dealing with mental illness. Someone whom can withstand the constant ups and downs of mental illness - and maintain a constant reminder of what your relationship truly entails; THAT is something you should both WANT - and NEED... So - make sure you thank your boyfriend - often times; not all the time. Thank him in ways he wouldn't expect. Shock him. Give him, "What words cannot describe... In healthy doses."
Another question...
Alright - suppose you DO have an illness. What kinds of things change the moment you realize that you do have an illness? Does illness run in your family? Or is it completely new? Have you researched alot about it?
IF there's ONE good piece of advice anyone would / could give you on this forum - or anywhere else on the internet... (SERIOUSLY) Save yourself alot of stress - and stop reading symptoms off of the internet! Its not a good thing. Everything that we write to you on this forum - is limited to what you have told us; and its also limited by text... The best thing to do - for OBJECTIVITY - is to sit down with a councillor; or a psychiatrist - and be 100% honest about everything. I'd suggest doing that if you haven't already done so.
Thanks,
8800gts