Girls, Why aren't I getting my period?

Okay so I got my first period back in October when I was 15. It lasted EIGHT days and then finally it was over. Then I had a second one around December and it seemed like it wasn't really a full period but more like left over blood (very dark, almost brown and it only lasted a couple of days). This also happened again the same way the next month (with the very little amount of brown blood). Okay so now it is July and I haven't had any periods since then. I do ovulate as I have some clear diacharge pretty much every month, but no blood. I also went to my gynecologist back in April to see what's up and they performed an ultrasound on me. They said everything looked alright and that I was releasing an egg and everything but still no blood. They also suggested that I go on "the pill" to help kickstart my periods but I don't feel very comfortable doing that. So what's up? If you could help calm me down and give me some insight on what may be going on that would be great! Okay thank you :)
Girls, Why aren't I getting my period?
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