Please help

I had sex in August and later that month I had my period, I also had my period for September too. Then I start stressing thinking I’m pregnant and stuff so now it’s October and eve says I’m 2 days late which making me more scared you know. And I can’t take a pregnancy test because my parents don’t know I’m you know having sex and Ik some of you will said if I’m old enough to have sex then I need to own up and buy a pregnancy test but you see I just can’t do that. I have really strict parents. I think I’m late because I’m stressing about thinking I’m pregnant. And I don’t have know pregnancy symptoms. And if I was pregnant why would have my period August and September but you see I’m paranoid. Sometimes I have cramps like you know when your period about to start... yeah and I’m just scared please don’t be mean. What do you think this is?