Depression. What are some ways to overcome it?

I'm 15. I'm a sophomore in high school. I have ADD, generalized anxiety disorder, and mood disorder ( I have symptoms of depression and bipolar disorder). I've had depression for probably 5 years now. But I finally started going to a therapist and got put on medication two years ago. But it's gotten really bad to where it affected my life choices and my education. But I take medication and I go to a therapist and see a psychologist. I'm not suicidal at all and never have been. I don't know why I'm so depressed. If I knew what was causing it I'd fix it. I'm pretty shy and over the years I've just isolated myself in my house and never go out and do things. My phycologist said it was a habit and I need to work on it. So I tried and have been trying to go out and do things. But I'm still not happy and I'm still depressed. I'm just really tired of dealing with this and not being happy and positive and just not enjoying life. If any of u have had depression, could u please share your experiences and how u overcame it and how u got through it? Also if u know any tips or anything that could help me overcome it please let me know. Thanks :)