NEED YOUR HELP

OK. I need your help. Period ended Nov 27th. It was very heavy and lasted for 7 days. I started taking opk a few days after and everyday was negative. Usually I have a 28 day cycle but I did get my iud removed on Nov 6th. I went to the gyno on Dec 5th because I suspected I had a UTI. When my gyno checked me she said it looked like I was in my fertile window based on my cervix and cervical mucus. Of course, I had sex the day following. This past weekend, I was beginning to cramp. My breasts were sore and I could tell my basal body temp was up especially this past Sunday. I took a opk test this morning and it was positive. Could I be ovulating this late in a cycle? Anyone else experienced this? I am very confused and just need some input.