Gender guessing

I'm 13 weeks and me and my fiancé can't stop guess at what we are having. With our girl, I was sick but tolerable. This one is worse. I have been to the dr more times than I should for sickness. Colds. Fevers. Eye infections. And I've jus had really bad morning sickness and horrible heart burn!!! We really want a son this time. N he says if it's girl, he gonna try again for a boy! Lol. Did you guys have any good guessing games or ways to find out what you're having????