mm.. sounds like a battery or alternator problem
I would sooner say alternator because of how you said it won't move below or past 11. I would check to see if it was still working by taking it to an Autozone or somewere that has a battery/alternator check unless you have a volt gauge that can handel the amount of volts your car is putting out.. which you probably don't have. but you may be looking at a new alternator man.