I am sooo sorry that you are battling this problem right now. The one thing you have to stop doing is don't put yourself down or under estimate your capabilities as a person wanting to succeed in life. You can be whatever you want to be if you go for it! Depression is a sad state as all of us know and can interrupt lives but if we can become stable to a degree, with the proper medication and support.I'm sure your parents would support you no matter what you did.
One thing about life is that we all have choices. We can choose to be a success or a failure. We can choose to be a model student or an under acheiver. We can choose which path to take when we become adults. The thing with that is if you take the wrong turn or go down the wrong path in the fork in the road, it's no too late to go back and take the right path and then continue on with your journey to a good life. After all my years, I can safely say that we are all accountable for our present and future lives. Some of us, like the people here, need help, compassion, consideration and a boost of confidence. You are young. Don't count yourself out yet!
Prayers coming your way
There is no such word as can't. Can't simply means wouln't. Grab as much as life as you can. Future is a long way away for those who don't believe. Don't build a foundation of life on sand. It will take it away with the tide. Love a little more, be unkind a lot less.