One thing that might help you is going to your college's disability services. I don't think that technically depression is classified as a disability, but at least at my college disability services will help you with mental health issues. With people I know, the have allowed students more time to turn in assignments, provided classrooms for people to take their exams by themselves if being near other people caused anxiety, etc.

I know it can sometimes feel like depression is just an excuse -- I feel that way sometimes too. But it is important to remember that if you could do the work, I think you would. The fact that you are caring about how you are doing academically shows that you want to do well and aren't just blowing things off for no reason. Depression has a biological basis and is not just an excuse. Get the help you need and deserve!