I’m 15 and my bf is bisexual

So I really really need some help because I’m finding stuff really confusing. I’m 15 and I’m in my first relationship with this guy who is bisexual. We have dated for three months and I have only just found out that he is bi and that he has sucked off some guy to experiment. I really liked him cause I thought he was innocent and always told me he’s never done anything more than kissing and i liked that cause I haven’t done more then kissing either. But the thing is he knows he’s def into guys but how do I know he’s defiantly into girls because he’s never done anything sexual with them? And I’m scared for him to try with me cause if he doesn’t like it then I’m gonna he really upset and hurt. He tells me he loves me and stuff and I believe him but it just seems odd that he’s done stuff sexually with guys and never with me. He tells me he’s more attracted to girls but how would he know because he’s never seen a vag before, he’s only experienced guys. I really don’t know what to do because he might be gay and I’m 15 and this is my first relationship so I’m finding it all very new and I need some advice!