Nervous about having sex

Okay so me and my boyfriend have been together nearly a year, and I think we are heading in a more sexual direction if ya catch my drift ladies😉 We haven't done anything sexual yet but even though I'm nervous, I know that I'm 100% ready as I trust him completely and know for sure that he'll make it as comfortable as possible for me. The thing that worries me is the actual sex part, his dick is about 8.5 inches and he's 6"5, whereas I'm 5"8. To be honest, I'm just scared that I won't enjoy it, find it pleasurable or maybe that he won't fit? I do feel that we would be prepared, but the only thing that confuses me is whether I should go on the pill or not? Oh and we are both 17 years old. I would really appreciate your guys advice!💗