Missing Period but On Birth Control

Hi guys 👋

I'm writing on this forum mostly to get some peace of mind. I've missed my period for the last two months. I am on birth control and haven't missed my pills. I am used to having irregular periods. I've also taken several pregnancy tests and they all read negative. The doctor told me that this is normal because I just started birth control in August, but it is still nerve wracking. I thought I would miss my third period, but I ended up bleeding for two days. Does that count as a period? Does anyone have experience with this? Is this actually normal? Should I just wait until my next period to make a doctor appointment since I bled for those 2 days?

PS I don't know if this helps but I'm 18.