Period irregular.

Eme
My period has always never been on time but lately it has been like 2-3 months off!!! I took PR tests( negative) and went to the doctor. They didnt seem concerned. Should i be worried there is a problem. 
I had 2 baterial infections the last one I had a fever and took forever to figure what was wrong. I had a fever for like over a wk!! The doctor finally did a blood culture and found baterial infection and linked itto last one!! Put me on antibiotics and I got better.
My period used to skipa few days to a few weeks. Now I maynot have a period for 2 or 3 months and they dont alwayslast the full 7 days likethey used too.
Please give my advise or help!!