Hi ((LittleForgetMeNot)) - I'm sorry you're struggling with depression. Have you seen your family doctor and considered taking medication? I think it would also help if your parent speaks to your teacher and principle - they should make things like presenting and group projects easier - meaning the teacher might let you present just for the teacher and he/she might assign you to a group rather than the 'dreaded joining' of a group. Letting the teacher know might give you some relief and not feel so alone. I think you should try to go, even if you don't feel like it. I also highly recommend doing some vigorous exercise, even if you don't feel like it. Try the regular exercsie for a month and see how you feel.
I went through a bad time 2 1/2 yrs ago and I was really struggling to feel motivated. Since I have 2 children I had to get moving, even though I didn't feel like it. So I ended up literally forcing myself - I call it 'robot mode' and I get moving even though my hearts not in it. Sometimes I ended up feeling a little better but I always felt proud that I accomplished tasks despite feeling emotionally crippled. I'm hoping you can do the same so you won't end up behind. I hope you feel better.