How do I live through such an early bedtime?!?

Sweetie. That's seriously a bummer. For the time being you should put things in your room to occupy yourself until its a reasonable time to go to sleep. Then you should thing of a bet to make with your mother that you can actually win. Pick something that she doesn't know your good at or something that shes particularly bad at. Then say, "Mom, how about this? If you beat me at _____ then I will do the dishes for the rest of summer, if I win, me and (your sisters name) can go to bed at (your regular bedtime)." Should work. Good Luck!!