Implantation or Period Trying to Come?!

So I just had my HCG beta early this morning (14dpIUI) and a couple hours later I had a small amount of light pink spotting and am still having some light cramping. I’ve always been a bit of a late ovulator so we also had sex the day after the IUI as well. I should get my results from the beta later today, but would it even be positive if I JUST implanted?? I’m on progesterone also, so maybe it’s my period trying to break through?? Anyone else have late implantation?! I’m really not sure what to think.