Freaking out a little

Okay so I'm having some major cramping but my periods light like barley any blood... I had my period last week and I'm on the implanon birth control. But just to give a little back story to this... me and this guy I knew for a while now started working together and we've got really close the past few weeks. An well one thing led to another. The sex was phenomenal!! Ladies I have such a hard time getting off during sex but with him it's a thing of the past. Sex has also hurt but I believe that's because he's rather gifted if you know what I mean... idk he jokes about how fertile he is but I've been on the implanon for 2 years now An had no problem with it. I guess I'm just freaking out because he's got two girls and I've got a little boy. So if things went further we'd have a pretty big family. Can somebody calm my nerves? Or is there a reason I'm freaking out