can’t stay wet..

So i’ve been with my boyfriend for about 3 months and the first time we had sex I was extremely wet and turned on in the beginning.. but then it was gone. I brushed it off as normal because my parents called me in the middle of it and really just ruined it. But then we tried again and it just disappeared once again. I love being with him & he’s honestly very sweet, but he’s a lot smaller (down there) than my past partners and I just don’t know what to do.. I’ve thought of everything. i’m on a new birth control, that could be it? but now i’ve begun to worry that maybe something is wrong with me.. he’s also much less experienced than my other partners and i’m used to someone being in control.. i’m worried this will ruin our relationship.