I know you said your mom will not believe you are depressed, but you must talk to her about how you feel. Ask her to take you to a doctor. Let her sit in on the consultation. You will only know if you truly have depression or bipolar if you talk to a doctor.
I know it will be hard, but you cannot do this alone at your age.
Hi...it sounds like something is definitely going on which warrants a visit to your doctor. Talk to your mom and tell her exactly what you told us, so she can see the seriousness of this. Sometimes as parents we don't want to accept that our child is struggling with something, so you need to really impress upon her how bad this is. If need be, put it in a letter to her, we really hear what is being said when we have to read the words. Know you're not alone sweetie, we hear from many young teens. The things that are bothering you from your past are playing a big role in this and with therapy you can resolve those issues and ease your depression. There's so much help for you, you'll feel better with some help. Don't be afraid and talk to your mom.