Bec just a super quick one. The corpus luteum cyst is the cyst in which the egg jumps out of the ovary. Its basically the follie in which contains the egg when you ovulate and it produces progesterone. If you don't get pregnant that cycle the corpus luteum cyst is reabsorbed and the new cycle begins (with AF) If you get pregnant which you did the cyst increases in size and produces the progesterone until the placenta takes over (fully at around 12-14weeks) so every lady that ovulates you can see the cyst on scan and thats why they can tell which ovary produced the goods for that month. In pregnancy they can get huge which is completely normal but they can be very painful. Mine with J was so painful it was actually more painful then my ectopic pregnancy. I was sure my tube was rupturing but 3scans later showed no ectopic. So I'd say your completely normal. And yep normal to be painful.