21 and thinking about having sex for the first time

I'm a debout Catholic but I think I've found my soulmate and I don't really believe in waiting anymore. I'm 21 and in grad school, and we've been dating for over a year and it feels silly to wait when we've both been talking about marriage for a while now. I feel like I shouldn't be so worried about sex as an adult with her head on her shoulders. But I'm scared. It's super frustrating to wait, but I'm also worried I'll feel guilty after sex. Any thoughts?