Unfair

So I have a friend that's been pregnant twice and she doesn't want kids, so she's had an abortion both times. She knows i don't approve of them, but it's her choice, so she can do whatever she wants.

But every time I've thought I was pregnant and I take a test, it's negative. I have PCOS, but a lot of women with PCOS can get pregnant fairly easily. So this is really frustrating to me.

Why is it that the person that wants kids can't get pregnant, but the one that doesn't, has been pregnant twice?