Scared

I don't know why I'm freaking out over this but I'm still kind of scared. I have only had sex twice while not on birth control and we used protection and me and my boyfriend still continue to use condoms. I have been on birth control for almost two months and  had a normal period the first month and I haven't gotten to the placebo pills for my second month but for some reason I'm still scared I could be pregnant. I know it's a really slim chance especially since we have been so careful and we have had no accidents so far as well as me having a normal period. I guess I'm just confused because some of the side effects to birth control are similar to pregnancy symptoms. Having some feedback would we great. Thank you