Irregular Periods, Sex, & Birth Control

So my boyfriend and I started having sex a couple weeks ago and we aren't using a condom but he pulls out everytime and I'm on birth control. Now this may be a bit of an overreaction but I can't talk to my mother or anyone else about this because my family is all about image and if it got out that I'm having sex before I'm out of high school my parents would flip out, so I figured maybe someone on here could help a girl out. I'm 5 days late for my period (this happens a lot)(my periods are really irregular) but I'm experiencing a bunch of period symptoms and I'm scared I'm pregnant. I'm also confused because I was put on birth control to help regulate my periods and 
A. They aren't regulated and I've been on it for about 5 months
B. I've been told that if ur put on it for regulation it doesn't do the protecting from pregnancy thing 
C. If it's not working for the regulation thing, how do I know if it's still keeping me from getting pregnant 
Anyway I would really appreciate it if someone could help me out. I'm just worried and confused and extremely alone with this because bless his heart, but my boyfriend is just a bit clueless.