Help Advise

Is anyone trying for baby number 3? Well my bf and I have had unprotected since January of this year and he has pulled out. I was hoping I could just unexpectedly get pregnant anytime and it's not happened yet. We have 2 amazing girls and I know he secretly wants a boy. I have had all of these thoughts and I'm thinking he doesn't want me to get pregnant cause he is afraid it will be another girl. I read somewhere that your chances of having a girl for the third time are low. I really want to convince my bf that I want to try for baby #3 soon so my kids will be all three years apart, I just do not know what to do. Any advise.