Carrying low.

I'm convinced I'm having a girl, I'll be ecstatic either way but I'm 15 weeks 6 days and everyone says because I'm carrying so low it's a boy but my theory is, my uterus is barely up to my belly button, that's probably why I'm carrying low. Does anyone even believe in that old wives tail? Also will my belly lift up as my uterus does? Is that how it works? I'm a first time mum