Feeling a little bit of everything... any advice?

well.. I had a mishap, took plan b on june 2nd, got my period on june 8. I was told that was breakthrough bleeding. After having this breakthrough bleeding, is it still possible for me to get pregnant? I want to add that ever since this incident, I didn't carry on any ual activity and I wasn't already pregnant from before. It's almost july and my period is due in another week or so. I took a blood test 14 days after having breakthrough bleeding and it was negative. I took this on the 17th. What's the chance of me being pregnant after getting breakthrough bleeding a week after taking plan b right around the time I have my normal period and not carrying any ual activity since and also not being pregnant before the incident... I'm just scared I guess, really want that 2nd period to come... anyone have the same incident? also, how often do women get their second period late or early after taking plan b. I repeat, not 1st period breakthrough bleeding, by the 2nd month's period? thanks