How does the Church feel about using fertility drugs to assist natural conception? Is it morally licit? Why or why not? I thought it was when we did but I had some second thoughts.

To preface, my wife and I have struggled with infertility for several years since we were married (over 2 years, we had 2 early miscarriages that were too early for doctors to even detect). The main issue is that my wife rarely ovulated when she was supposed to, and consequently conceiving was impossible even if we did everything right. We prayed over it and eventually decided to explore treatments for infertility that didn't involve violating Catholic teachings.

My wife was accepted to do a trial run with a fertility specialist last year, and we laid down the law right away and said no IVF, no IUI, no surrogacy, etc. They prescribed us to try letrozole, a fertility drug commonly used in conjunction with IVF treatments. For those who don't know, letrozole is basically an "anti-contraceptive" - instead of suppressing a woman's fertility cycle, it stimulates it. They use it for IVF to get a big supply of eggs to "scoop out" and use for the IVF. We obviously said that's not an option. My conscience told me that using the drug to assist a natural conception was fine, though, because it isn't subverting the marital union as IVF does, or done with the intent of freezing or dumping our child's brothers and sisters - it's just fixing a defect in her cycle like glasses fix a defect of vision.

The drug did exactly what is was supposed to do. My wife, who had maybe ovulated 3-4 times over a period of 2 years, ovulated 6 months in a row without fail on the medication, but sadly, none of those times gave us the baby we had prayed for. We eventually stopped using the medicine because we couldn't afford it anymore due to a change of health insurance. We were disheartened at missing 6 straight chances, and decided to leave it up to God if we get children naturally or are called to adoption.

But then, something amazing happened. My wife started ovulating again on a normal cycle, without the medicine. I don't know if it was God rewarding our patience, or the medicine kicking her hormones "into gear" (or both), but she was finally doing what losing weight, eating right, and exercising couldn't get her to do.

In the second month of her ovulating off the medicine, she got pregnant for real, and we are expecting a daughter this year. She will obviously be baptized and raised in the Catholic faith. The only thing I'm wondering is if we did something wrong, and maybe there are other reasons why the Church is opposed to these drugs. I'm sure the companies that make and profit from the drugs also profit from IVF and other immoral medical procedures, but that would seem to be the case for just about any medicine you used. Did we do something wrong?