> Since my Olenna is younger her birthday was two weeks before mine

Wow, this doesn't make sense at all. Also nobody in your family seems to understand birthday cakes if they think it is just for one person. And your parents only put you in therapy because the school forced them???

Seriously, the only fuckups here are your parents. Do you have anyone else to support you, e.g. a grandparent or a close friend? It sucks to have family like yours, but you should know that you can build close relationships with other people and that you are under no obligation to keep in contact with your parents once you move away.