Help!

So I had protected sex on August 30th. I got off my period on the 28th of August. Then on the the 31st I took the plan b one step pill because I feared some of the cum might've can out the top. A week later I started bleeding as if I had started my period but it was only for 3 days. Not knowing whether or not it was my period I put it into glow. That moved my next period from the 24th of this month now to the 7th of October. Was that my period? Also, if it wasn't  should I go by the original date of the 24th or the new date of the 7th? I haven't started yet and need to know when I can take a test and get the  most accurate results. I also know that I'm not regular sometimes either. I'm hoping I'm not pregnant.