Okay. So I'm A Fifteen Year Old Female, And For

Okay. So I'm a fifteen year old female, and for the past two days, it's been feeling like there are small bubbles at the entrance of my vagina. If I move my legs a certain way, they go away, but then they come back a couple minutes later. My mom says that it's normal and a part of my period, which for me, has always been a little late. But I just want to be sure
(I'm also a huge hypochondriac, so I've been stressing and stressing big time lately and I just want an answer..)