Firstly; I admire you for still working hard at school with depression, you've clearly had to work really hard. Well done.
Secondly; a B average is very good really, especially in your circumstances. I have no doubt that you could get into a decent college with that grade, it's clear you work hard too.
I think all you need to do is work on how to deal with your stress and depression and you can work to the best of your ability. Have you seen a specialist? Have they recommended anything? If so, keep working on it.
If not, here are some things you can do;
Confide in trusted friends or family. It helps to try and explain exactly what you're going through. Not only can they then begin to help you but after going through it, you fully understand why you feel this way.
Try and keep up with a social activity or group. When you feel depressed, it's so tempting to shut yourself away from other people and stay by yourself but it actually helps to be around other people and will help you feel a bit better.
Join a support group especially for depression? I know this might seem a bit over the top, but talking to someone else with the same problems really does help you to understand what you can do to help yourselves. It reduces your sense of isolation. If this isn't ideal, try joining a website aimed at your problems? You may find answers there.
I also think you need to learn how to manage your stress. I suffer with stress, big time, because I worry too much and find it hard to relax; obviously this doesn't help at all.
When you feel stressed, stop for a moment and try and change your reaction. If you hear something stressful or have a lot of work to do, step back and react positively; even if you don't feel like it. Put a film on, grab a hot drink, take a nap or play some music. This sets you up in a better and relaxed mood to get your work done.
You can't completely eliminate stress because something will always put the pressure on a little bit but ways to reduce it could be;
meditation
yoga
deep breathing from your diaphragm.
If all else fails, try punching pillows or buy a stress ball to squeeze when you feel the pressure. There are ways around it
I really hope you feel better soon and I hope this is of some help. Good luck with your schooling!