I can relate. It seemed like every Bday something bad would happen. One time I got randomly punched in the eye at school when I was around your age. Another few ones relatives got very sick/hospital. Etc.
Now when nothing bad happens, but nothing fun/exciting happens and my b-day is a bore I'm happy about it. I know someday I'll have a happy one. The hollidays and stuff too aren't too great for me right now but I won't get into all that.
Just remember as you get older to plan ahead and don't let other people interfer with your progress. If you can get a head of other people or at least stay with them in starting your life you will feel great. Fall behind and it can get to you, but don't let it, it's never too late to start doing something. Don't think about well I should of, or I could do this, just do it and get it overwith like going to college or whatever. If you always wanted to do something but never did, start doing it now. Whatever it might be. (say, lifting weights, whatever!)
Things can't be bad forever, there will be a point in your life where you are free to make your own family/life/whatever. "Scars make us tougher".
I've found the only person that truly looks out for myself, is me. You are the only person who is always with you, so you have to remember that. Be your own friend sorta speak.
Hope that gave you some "hope", even though it won't make things better now, just hang in there and be proud that you can deal with whatever comes your way and you will get through it.
I hope I made some sense too.