Am I pregnant

I’m 19F been using birth control almost 8 months I only took a break on 22th of July and then get back to it when I got my period it was 26th of July and my boyfriend was out of town for a month and we had sex on 23th of August when he came back and I took a plan b just in case but it’s been more than a month and I still haven’t gotten my period yet i took pregnancy test at 19th of august and it was negative but i missed my birth control time to time but only with 1-2 hours of forgetting I don’t know if im pregnant, I am keep getting period pains and they are really painful time to time but I have no signs of getting my period other than the cramps please help me out I want to take action as soon as I can.