Hey, i am sorry to hear you are having such a bad time. I am around your age and know how hard anxiety can be and how it ruins <YOUR> social life. while my friends are out having a social drink, i am at home as alcohol makes my anxiety worse and i find going out in town at night quite stressful.
From what you have said, having all those tests, it looks like you are healthy. Anxiety can play horrible tricks on you and make you think you have something physically wrong with you when you don't. i've lost how many times i've thought i had physical illness. after i have a episode of anxiety i feel really tired and just want to sleep and don't want to go out. i've thought the same as you about having m.s. and cancer.
as tough as it is, you have to realise that these feelings and thoughts are purely a result of anxiety. you are the only person that can stop them. its not the power of anxiety but the power
you give the anxiety. if you think "i'm going to feel anxious" or "i'm not going to feel well" then its highly likely that you will feel anxious and unwell. it's a vicious cycle. i think therefore i am. but by undetstanding and accepting this, you can start to help yourself.
i've dealt with anxiety for 5 years and the majority of the time i am fine (although its never fully gone) and i live my life but i have days/weeks when it plays up. i just stay strong, get through it and it gets better.
right now they are playing up and i have a routine eye test (i just like to be reassured that i dont have a brain tumour) and a foot appointment. i find these both quite stressful and as much i would like to cancel them both, i love the feeling of knowing that i did it and stayed strong. i'll let <YOU> know how i get on.
hope this helped
don't hestitate to post and i will do my best to help. i know how lonely it can be. xxxxxx