what is my body doing? :(

I came off BC at the start of November 17, I had a period at the start of December, then again at the start of Jan, a week after my Jan period finished I got some really unusually heavy bleeding. it honestly didn't seem like a period, everything about it was different, I saw the doctor had a blood test all came back fine. my next period was due at the end of Jan but it's a no show. I've done a test and it's negative. what could be going on? I'm so confused, my period is usually very regular.