Baby’s Heartbeat❤️

Hey guys, at 12 weeks my baby’s bpm was between 171 & 174. I went to a prenatal appt yesterday at 14 weeks and baby’s bpm is now 131 , has anyone ever experienced this huge decrease in there pregnancy and everything was normal? I asked the nurse but she wasn’t much reassurance, she just kinda brushed it off. Also I was told by friends it would be a girl because she had such a high heartbeat but now it’s 131 idk I’m just probably paranoid but any advice is greatly appreciated. Thanks!