Help me please I'm really confused

Ok so me and my bf had sex on Friday June  20th and according to my app I was suppose to ovulate that day and I'm pretty regular. So I told him we needed to get plan b we did but on that Saturday afternoon. Then two weeks later I got my period but it was lighter than regluar. Then on July 30 I started my other period but it was lighter than the previous one and the in sept. I have not gotten my period it was suppose to come on the second but nothing yet. I took to store brand tests but both were negative. Do you think I might be preg?