I'm 16, And I Just Started Taking Birth Control In

I'm 16, and I just started taking birth control in July. my doctor said I could start taking it whenever so I didn't really read the instructions that said to wait the Sunday after your period starts so I was supposed to get my period on a friday and I never got it that month(also when I went to the doctor they told me I have anemia, if that matters). I am sexually active so me and my boyfriend decided to take a pregnancy test, we took two, and they were both negative. I didn't get my period in August either so we took two more pregnancy tests and they were negative. I had all my pms symptoms when I was supposed to get my period the past two months I just never got my period. I'm supposed to get my period in about 5 days. the past two times I've had sex I've started bleeding during. I forgot to take one of my pills on the 4th, but I took it once I remembered in the morning and I bled a little and I read that's normal when you forgot to take a pill, at first it was just a little bit of spotting but it kinda got heavier, and went away again, and I start bleeding during sex. so my question is what's up? is it my birth control? am I pregnant but don't have enough hcg for it to show up on the pregnancy tests or what? the birth control im taking is the seasonique extended cycle I think it's called, so I'm supposed to skip two and periods and get it the third month but I'm pretty sure it wasn't supposed to start working immediately the month I started taking it. I'm really worried, help!