Baby's heartbeat

I have a Fetal Doppler and have used it since I was about 9 weeks. My babies heartbeat has always been found low near my pelvic bone but this week that has changed. I am now hearing his heartbeat next to my belly button and have all week. I'm trying to figure out where he is positioned. I'm 31 weeks tomorrow. Any ideas ladies? I feel like it means he could be breached.