When to know when you're "ready"?

Diana
i've been together with my boyfriend for a while and sometimes i can be reallllyyyyy in the mood, and other times eh. 
I've always had the idea that I wanted to wait till marriage but also, it wouldn't hurt to  have sex now. I'm still a virgin and I guess i'm just trying to figure out if it's just hormones and i'm not emotionally ready??
How would i know though?