Had unprotected sex on the 3rd took plan b 45 min later.my expected period was on the 9th . got heavy bleeding the 10th am i pregnant?

Maybe not, but...: Plan B can alter the menstrual for the cycle in which Plan B was taken, and sometimes the next cycle too. One should be sure to check a home pregnancy test about 3 weeks after sex, because Plan B works most of the time, but not all the time.

Probably not: Plan B is 95% effective if taken within 24 hours after unprotected sex and does cause abnormal bleeding so you are probably not pregnant. To be sure, do a pregnancy test and repeat it in 3-5 days if it is negative. Now is also the time to look into a more reliable method of contraception so you don't have this worry again. Best wishes.