hormones are messed up I think?

So one month ago I had sex with a condom on like a day before my fertile window would start.  I'm pretty sure the condom broke or his cum leaked out not sure but that could be a real possibility so later the next day I took some plan B for the first time. I started my "period" again about 3 days after taking the pill. That lasted for about 3 days, I was really hormonal I was irate and happy at the same time it was very intense and it wasn't cool at all. Now this is about a month later since I've taken the plan B and I haven't have another period. I've had lots of migraines and I've been nauseous a lot but only at night.  I missed my last one which was supposed to start on the 19th , now my plan b "period" is due in 3 days. I can feel a period coming on but I've felt like this for like 2 weeks, it just hast started yet. I took a pregnancy test like a week and a half ago and it said I wasn't pregnant , but maybe I took it too early