What could cause irregular periods, sensitivity to smell, and abdominal pain in a woman despite testing negative for pregnancy?

Hi doctor,

I had undergone hysteroscopic dilation and curettage for endometrial polypoidal thickening. I got my period after two weeks and it has continued for seven days. Later, I started using tablets for my thyroid and I started to get spotting. I had heavy bleeding for one hour after two days. Afterward, there is no spotting and periods happened to me. Usually, if I start bleeding on the 15th day of the cycle, it could last for seven days. However, this was the first time I experienced heavy bleeding that abruptly ended. I tested negative for pregnancy using both a human chorionic gonadotropin and a home pregnancy test. The results of my thyroid test were also normal, and transvaginal sonography revealed multiple follicles. I am having all the symptoms like feeling nausea and being very sensitive to smells. I feel vomiting sometimes when I smell coffee and also feel cramps in my lower abdomen. I had polycystic ovarian disease before marriage but it shows normal. Am I pregnant?

When I searched online it says that human chorionic gonadotropin will not show up for twin babies and also says that it is not good to ovulate when pregnant.