HELP!!!!

I'm 12 and my periods are still irregular at least I think they are. But I haven't gotten it this month it's only the 18 of November but I'm still scared that I might be pregnant. I don't want to ask my mom about it. Cuz you know....embarrassing!!!! So I just came here to ask this. What should I do?? I thought it was just weird because on my home page it says that I'm 6 days late and I have a 7% percent chance of being pregnant. When I first got the app I told my mom about it and she said it might not work because I'm still to young and they're probably irregular. It's just worrying me