Late period

My period is about 2 days late. I have implanon, my partner and I have been fucking like rabbits and never worn a condom so he's cum in me every time. Last time we had sex was Tuesday, period was supposed to start Friday and now it's Sunday. I've taken 2 tests, one on Thursday before my period was due and one on Saturday, after my period was due. Both came back negative, should I test again in a week? Or just wait and see?

My last period was a few days late, could it be a normal thing?