I have a lot of your feelings, although they do not feel as intense as yours. I am a student and the lab where I study has many people who you meet randomly during the course of things, and everything is all 'hi, how are you?' smiles etc. etc. most of the time I dread this even making eye content and it gets me angry how false people are and can't bear to talk to most people. Sometimes I've got as far as the car park and just can't get out the car just because I can't deal with seeing people and interacting with them. Also socially, unless I've had a few drinks I try so hard to keep a conversation going and my face hurts too with trying to smile and look interested.
Also you mention little things like people walking too slowly, queueing etc. I too get very wound up and can feel myself cursing very loudly and out of control in my head with evil words that would shock anyone who knows me! I also can get road rage quite easily. Fortunately it has not been so overwhelming for anything to physically happen...yet....
I sigh relief 2 when I get in. I need time by myself and get very wound up and stressed and have feelings like I can't cope when I haven't had much 'own time'
I suffer from depression and like you thought I could do it on my own and that it showed weakness since most people cope with their feelings but rather than weakness it shows strength of admitting you need some kind of help, whether medical or otherwise and although people who don't suffer from depression may see it as a weakness, I don't, and I'm sure the doctor could offer some kind of help. You are not alone, who gives a shirt what anyone thinks, you are obviously not happy......good luck on your decisions and if you need to vent anything do it here cause it does help (perhaps I should look at my own advice!) I'm here and will reply again if you wish
r12las