Almost 4 days late any thought suggestions

So me and my man had sex a few times during ovulation. ..and also a few times right before and after. Two weeks after af came last month we had sex and there was a tiny bit of blood. Nothing else after that....and this month no af still almost 4 days after supposed to come...I've already taken a test before missed af and yesterday. But both negative this is weird to me Cus I usually start af on the days shown