I had a (dermoid) cyst removed during my c-section with my second child. It was the size of a grapefruit and we didn't know it was even there. They had to remove the left ovary along with the cyst. Dr said my fertility shouldn't be affected, as all you need is one ovary, and it will ovulate every month, in place of the missing one.
Sure enough, my cycles were always normal after that. Period and ovulation were like clock work.
We started trying to gett pregnant in October of 2014. I started having pain in my right side around that time. Ultrasound showed another, smaller, dermoid cyst on my right ovary. I was very worried that the cud would take over and I would lose that ovary too. I didn't know whether it was better to have the cyst removed or keep it, and continue to try for a baby.
I was not getting pregnant and was about to make the decision to have surgery on the cyst, when I finally got pregnant 17 months after I started trying. I don't think the cyst is why it took so long to concieve...I had an hsg done and got pregnant soon after.
Do what is best for you concerning removing the cyst, but just know that it is MORE than possible to get pregnant with one ovary that has a cyst on it!!!
I'm sorry you've been through all this! Since you have one ovary or at least part of one, pregnancy is possible although it may be more difficult. Of course, you will want to watch this current cyst carefully and not let it get too big so it can be removed easily enough without obliterating your ovary. But then again, you don't want to undergo surgery unnecessarily due to risks including formation of scar tissue (adhesions) that can cause problems including infertility. In my opinion, 3 months seems a little long to wait for another ultrasound.
Hopefully, your gynecologist has excellent cystectomy skills if you do end up needing surgery. You may want to consult with a reproductive endocrinologist / fertility specialist if your current doctor is not one.
Best of luck to you and please keep us posted.