So I'm totally clueless on "lady business" medical terms even though I have already been pregnant twice.

I went to the ER yesterday (1/22) because I had a sharp pain for about 20 minutes in my lower abdomen on the 19th right before AF was due (note: also had ewcm on the 18th) and my aunt was just diagnosed with cervical cancer so I got it checked out. AF was due the 20th but I just got my IUD taken out in December so I figured my period is late due to that and the ewcm was also my body adjusting to not having the IUD.

They did an ultrasound and found a cyst in my left ovary. However, they said it could either be just a regular ovarian cyst or a possibly corpus luteum.

I looked up wtf a corpus luteum is because I suck at being a woman and have no idea. From what I read, a corpus luteum is developed after ovulation and produces progesterone to help support a healthy pregnancy. My pregnancy test at their office came up negative and they didnt find a sac or anything on the ultrasound.

My question is, is it possible that the pain was ovulation pain even though it was the day before AF was due? Did I ovulate late or something? We had sex on the 18th, so if I DID happen to ovulate on the 19th, would a "corpus luteum" mean we may have gotten pregnant and just too soon to pick up on a test or ultrasound? If ovulation was the 19th, I'd only be 3dpo so definitely early. Is there still a chance?