When to have it

I'm so confused with myself and obviously I know it's hormones but I'm sick of it!! I'm 15 my boyfriend and I have been together for 3 years and it's completely real and everything. And he recently brought up that he wants to have sex. He's not the type that would pressure me in to it but I'm confused because some moments I'm all for it like wanting to and then the next I'm thinking about all the negatives that could happen and don't want to. It confuses him too!!😁