Plan B/Periods

So my last period started 6/25 and was EXTREMELY light...it was light to start and stayed light but on the 26/27 it pretty much disappeared. It did come back but it wasn't even heavy enough to have a regular tampon in...it ended on the 28.

I'm not on birth control. My periods usually last 4 days and are usually pretty light but I can wear tampons and saturate about 4 a day until the end of the 3rd day.

1. Does anyone know why this could be?

2. Does anyone else have really light periods like that? Sometimes they only last like 3 days....

On the 29th, my SO and I saw each other for the first time in a month. We're entirely exclusive. We had sex with a condom but it broke and so all of the cum went inside me. We immediately went to get a plan b. I took it within an hour. On the 4th of July, I started to bleed. It wasn't bad, only left a streak on a pad...then on 6/5 I started to bleed more. I saturated a regular tampon within an hour which I NEVER do. I've been bleeding heavily since (much more than normal and with a few clots here and there but very small).

I really really don't know what to think of it....I know you can bleed after taking plan b but I thought it was just spotting...

Also, I know I should see a doc but I made an apt for Tuesday and just want to know what you all think!

Thanks.