I have had that crap told to from older people when was younger,a lot of the time.It just a faze or its complutely normal you will grow out of it and quit being a drama queen.Guest what its not a just a faze I still have all thses problem and im way pass being a teenager.
You should really try to talk to your mother again and try and make her undestand what going on in your life and how it would help you to get some kind of therapy maybe give her somebooks on the subjest.That being said it doesnt sound like she really believe you.
Its really hard to get over this with no help from other people believe me I know but getting tapes and books about CBT therapy might help a little bit.
Only other thing I can think of besides that,is look around your community to see if you can find any groups that help younger people with these problems for free.Im sure that they must have places like that there.
Good luck