I'm 38. It took 2 years of TTC every freaking cycle to conceive DS. I was nursing his sister the entire time. She was night weaned but still nursed 8 or 10 times during the day for most of theat time.
The second year I cried a lot and was so scared that I was infertile. I tried all kinds of dietary changes, herbs, supplements, etc... I was ovulating regularly but my lutal phase was still being suppressed. It was only 9 days at the time I conceived. It was 6 when I first started ovulating and then gradually lengthened to 9.
I consulted with a few medical professionals (not a fertility expert) and man did they think I was just stupid. I got a lot of "She's to big to nurse, just cut her off.", "You can't possibly know you are ovulating.", "Breast feeding does not affect fertility.", "You can't get pregnant if you are nursing.", "Here is a prescription for Clomid."
I strongly believed that DD was still needing to nurse so stopping was not an option. I also worried that if I weaned and then still could not conceive that I would have made a huge mistake. I just was not willing to sacrifice
DD's happiness for a baby that might never be.
The cycle I conceived I had a nasty virus that had me breaking out in intolerably itchy hives with a high fever. I was given a prescription for something that basically knocked me out 20 hours a day for about a week (well, maybe not that much but I milked it for the sleep) so DD hardly nursed at all. I can't remember what half of my cycle this happened. But i am betting the abrupt slow down in nursing coupled with being close to the minimum 10 day lutal phase is what did it for me.