Well, to be fair, it's your parents house and rules. As long as you're living under their roof, you must abide by their rules. I'm 22 and I have an 11pm curfew Sunday through Thursday unless I'm working. On Friday and Saturday, my curfew is 2am. I follow their rules because I can't afford to live on my own yet.
Sadly... Until you move out into your own place you need to live by their rules. I know that sucks for you, but unless they can accept that you're grown up and an adult now, you're gunna have to learn to deal with it. Sorry. :/