Just a note about one or two ovaries. Even with two ovaries, we weren't able to have a second child, so it really depends on the health of what you have, regardless of number.
We had our only child when I was 36, almost 37. We had twins everywhere on both sides of our families (12-13 sets of them in just 2-3 generations!), but we just had the one. It took us about 9 months to conceive with two ovaries, but were not able to have another one. So, you never know.
After years of issues with cysts and ultimately an abscess, I finally had the right ovary and fallopian tube removed last summer at age 49. I still have periods every month. They were a little funky (spotty) at first, but now, they're regular again. I've been told by my doctor as well that the existing ovary will eventually take over the duties of both of them.
If I remember my biology correctly...a big IF...the ovulation and fluctuation of hormones is what causes the period in the first place. So, I believe the theory that your one ovary is doing the work of two makes sense to me.
P.S. Sorry, gotta tell the story...My mom's mom had two healthy kids in her mid to late 40s...no twins...no problems. My grandparents were born in the 1880s! And I know someone whose first child had downs syndrome when she was just in her late 20s or early 30s and the second one was fine. So, you never know. Every conception and birth is individual.
Sorry I probably wasn't all that much help, but I thought I'd throw in my two cents.