kinda same with my family... I'm the only son and my mom's EXTREMELY overprotective (getting better) whilst my dad is all laid back and doesn't care what I do
I actually find that you can't really do too much to make her less overprotective, that's all her business
But first if you want to help ya gf go out and have fun you have to tell her what to do!
I assume that your gf is quite smart and will go to college, tell her to tell her mom that once her mother's gone who's gonna be there? noone! she will have to go through all these changes all too quickly, these changes are to be done in highschool and not in college becuz once ur in college it's basically too late to change, it would also help if she kept moaning of how overprotective her mother is everyday
so when she's in college she'll be so happy that she can go out that SHE WILL GO OUT EVERYDAY AND DO THINGS THAT SHE WOULDN;T DO IF HER MOM WASNT OVERPROTECTIVE
another thing is that her mom controls who's her friend or not, right? she doesn;t want you to go out with eachother well this IS A HUGE PROBLEM, if she continues to be given friends then eventually her friends will find out and they'll all be like her mom chooses that girl's friends and in the end noone will like her becuz of that.
another thing, and this is prolly easier for guys cuz it involves controlling ur mom up to a point... I mean like arguing, when there's a party her mom might be like NO, well she has to fight back and say YES eventually her mom will get kinda tired and say, WELL YOU AINT GOT NOONE TO DRIVE YOU THERE or something like that, at that point you say YES I HAVE, MY FRIEND WILL PICK ME UP, see how that helps?
now my mom is still a but overprotective but MUCH less than before and now she even let's me go out to clubs if I argue VERY MUCH (yeah i got fake ID but who cares?, half the time those guys don't check ID... at least where I live)
anyways trust me if she doesn't start to do things by herself then she will get ruined in the future, tell her mom TO GET A LIFE actually make her daughter say it to get the point accross, I said and it was kinda scary but she started to do much more normal things and now never comes out with me unless I ask for it, after the age of 13 90% of her child's life is NON OF HER BUSINESS, that 10% are school grades and family reunion (which is not a lot compared to what else she has going on)
her mom's done a great job but now she's overdoing it if ya know what i mean