People have such funny ideas about age, it's the most subjective fact out there! My boyfriend is 25 and I'm 18, all my friends thought he was my age and all his friends thought I was his age. There's not THAT much difference, especially if you're at uni (it's a younger life stage), I think people grow up when they get spouses and mortgages (here's hoping). As far as the clubbing and casual sex thing goes, you find a mixture of people from 18 to 30 who are into it, and some who would rather socialise in other ways... So no, you're not old, just find some like minded people, I assure you, we do exist!