[Serious] Mentally Ill people of Reddit, what is your illness, and can you try to describe what it is like?

Well this is the first time I've gone out about this, I'm too afraid to get help or even consider it because since I'm only 15, so here goes (it will be very long and confusing and I may need somebody else to make a tl;Dr for me since I won't be able to). I am not diagnosed professionally for any of these "things" I have. I am severely introverted, to a point where I can tolerate the 2 people I can even call my friends for an extended period of time (about 8 hours in a severe situation), my family makes fun of me for being like this and even yell at me for it because I'm not "normal" in their eyes. I do NOT like social situations at all, it is a living hell just to think about being in one. The only ones I will gladly join into of I even choose to, is when I can be of quick and very reassuring assistance where I can disappear shortly after, like answering quick questions or showing someone a room 5 doors over. I can only tolerate a small group of people (4 in this group) for what seems like an eternity as long as it is the virtual friendship we all mutually share. I much rather locking myself in my office for days at a time than spending that time with my family and talking or playing. I can not handle being touched unless it is by my family, assuming they're touching my arm or hand, and I can't touch someone back in the same way. I am very self isolating and distant, enough to where I cannot be of any help to my friends when they feel bad, and one is severely depressed as well, so it creates a bad mix. On another hand those same friendships I share are unbreakable by me, I care about these people more than myself and it doesn't make my situation any better. As a side product of being like this, it gives me time to think. Enough time to think about everything I remember, which is everything I've done since I was 7 and it makes me feel terrible, like a terrible person which I have convinced myself I am. Another product of this is my intelligence. It is considered very high above my age level. In all aspects of school I excel at anything that is not english. I cannot understand how to write an essay, or read Shakespearean scripts. It makes me look and feel very (I'm sorry if this offends anyone) retarded as I have a 50% in English and nearly 100% in every single one of my other classes, of course foreign languages are applied to this but I am not taking them this year. In math, science, technology, and band/instrumental courses I excel in a way I can not explain. There's more that is wrong with me that I'm entirely aware of that I am not going to bring up here as I am not ready to come out with these yet. Thank you for reading, and this is not a throwaway account if it even matters

/r/AskReddit Thread