There is a lot to digest here..
I know how you feel and it always seemed to be a battle to get anyone to listen. The one good thing (that really jumps out from your post) is that your parents understand and are trying to help. Change GP's, ask for a referral to the mental health team.
With regards to 'not labeling kids', you'll find that GP's are very reluctant to label anyone with mental health issues. The reason they don't like doing this is because it can cause the patient to feel overcome by their diagnosis.
With regards to your mother and her being put on 8 different anti-depressants over a period of months sounds unbelievable. If that is true then I'd suggest you both change doctors. Anti depressants don't work instantly and to be switching through that many anti depressants in a short period of time just isn't right.