8 days late and don’t know why??

Y’all I’m so confused! So I’m 8 days late. Me and husband have only had sex like 2 times. Both times with protection and we checked both condom (he never got off so I mean come on) I don’t think I’m pregnant but I’m so confused on why I’m so late! I’ve taken 2 tests both say negative. I have had what I think is a sinus infection so maybe that’s it?