Abnormal Period?

Caitlyn
So, the summer after fourth grade, I got my first period. I had just turned ten, so it was kind of early. It would have made sense if it was irregular, but it was an every month thing. 
But, ever since seventh grade, my period has been getting less and less frequent.
I'm now in tenth grade, and I'm lucky(?) if I get my period twice a year. My last period was October 27th and it lasted four days.
I'm not sexually active and don't take birth control. I feel like if I take b.c, it could help it, but my mom doesn't want to take me to a gynecologist until I lose my virginity. 
I don't know if this is just excess information, but I just got my first (of three) HPV shot, but nothing's happened. Also, I get a lot of thick, mostly white, discharge, and it makes me uncomfortable.
I just need some help, ladies. Thank you in advance!