I'm sure your going a million miles an hour right now, time to take a break and relax.
Think, think what your putting your mother through, I'm sure she loves you and wants only the best for you.
Foster care is not the Answer!
Foster homes are full of teenage 'kids that can't handle it', at home anymore.
Nobody is going to care for you like your own mother, not in this life.
Raising a teenager is much harder on the Parent than it is 'being a teenager', believe that.
Understand that...the reality of it.
You are not alone in this, many teens are struggling this very same issue.
Biggest thing is to try and talk to somebody face to face.
Worse thing to do is talk to people your own age or move in with friends.
But of course if your mind is made up and you want to be placed in Foster care, just keep headed in the same direction and you will achieve said goal.
I urge you to relax and meditate on what you hope to achieve with your actions, what is your mother hoping to achieve by her actions?