Plan B and late on my second period

So I took plan b about a week before my normal period and it came as normal but was super light the first day then stopped the second day and then the 3rd through the 6th day it bled like normal.

I'm normally every 26-28 days and now I'm 8 days late for this next period. I have had sex between now and the last period 2/3 times but they were all using a condom. I took a pregnancy test when I was 5 days late and it came out negative.

This is my 3rd time (we do use condoms but have the worst luck with them breaking) I've used plan b and the last two times I had no issues like this.