Not Pregnant...?

A few years ago I was dating a different guy and I got pregnant, it seemed easily, the first and last time we used withdrawal. I had an abortion and shortly after, he and I broke up. It wasn't working. And having an abortion damaged a lot of what's WAS working.
My fiance and I now aren't trying for a baby but we're also not preventing, and we've been doing so for 6 months and so far, nothing. I'm not actively looking to get pregnant, but im wondering if anyone knows why I'm not? Last time it was just one time. This time, well, we have sex several times a week.
My fiancé is a bit older than myself but that seems to be the only possibility to me, unless my uterus was damaged when I had my abortion?