Help??

My boyfriend really wants to have a baby but I'm not ready yet. I'm on BC (been on for 3 years) and he finishes inside. I always have gotten my period. I got my period just last week but we had sex a week or 2 before. I am insecure about my size and feel like I've gotten bigger since being at school and not working out. Looking at myself I feel like my belly is kind of rounding a bit. I just got my period but is it possible for me to still be able to get pregnant???