This Mom needs feedback from teen girls please?

My daughter is 15 1/2 and, based on what I see and hear, I feel pretty strongly that she and her bf are on the brink of having . She says they are just fooling around. I am not being judgemental but I am not an idiot (neither is she) and we both agree that getting pregnant is not an option at this time in her young life. I have made an appointment for her to have her first gyno exam and discuss birth control options. We have a pretty good relationship, but she doesn't seem to want to discuss this issue. I want her to understand my concerns and actions are based on my love for her. What can I say (or not say) to her to let her know that this upcoming appointment is not a "punishment" or that it has nothing to do with the trust I have in her? I would also appreciate any feedback from other moms in a similar situation, that being that my ex and I have shared custody, and he's not on board with this appointment idea, as he has blinders on about his "little girl". Common sense? NOT.