Please please help.

In August I skipped a period for no reason and ended up being fine- I know sometimes you just don't get your period while on the pill. It's happened once more in the past too. 

I have felt fine all month (no pregnant symptoms), taken my pill consistently besides one day, but did not have sex at all until one week after that day, also, my boyfriend never gets close to cumming inside of me either, he always pulls out on time or before on time. I have been very stressed out because of school and work, and I have also recently gotten sick and I know sometimes those can delay your period too. I'm really not that worried that I'm pregnant because this has happened in the past but my mom is concerned, which freaks me out. So can someone please give me input? I think I'm fine, she's also getting me a pregnancy test within the next few days but I would really like some help.