Nub/Heart Rate Theory

My first is a boy, heart rate in the 140s pretty consistently!

I’m about 13 weeks with my second, heart rate 168 today. The US tech was trying to get a look at the nub to do a nub theory, she was thinking boy but then maybe girl. Then she said heart rate supports girl.

Any guesses?

To note - my cravings have been different, citrus and juice a lot. And I’ve been breaking out some. Neither of which I had with my son but I know all pregnancies are different!