Hi there. Thanks for coming to TeenHelp. We are happy to have you here!
Sex doesn't always work 100% of the time. Even the most passionate, experienced lovers have some sexual congress that is not ideal, or even just downright bad. I've had sex many, many times with many, many partners and there are definitely times where my body was just not into it. I often pushed it any way and that was a mistake.
Any number of factors could have influenced the way your body responded. My guess is that you just hadn't seen each other in a while and you might be out of sync. I would imagine if you keep trying you'll have more good times than bad ones, since you seem to be really into your boyfriend.
Another thing: talk to him about what is going on with you. Faking sexual enjoyment is never a good idea and it does a disservice to the one you love. I know you said you hoped it might make things feel better, and that's legitimate, but it's better to communicate with your partner about your sexual experience. Trust me on that one.
Good luck and
PM me if you need anything else.