Not sure about iron, but vitamin D deficiency has a negative impact on fertility.
Are you BF? I'm surprised your acu gave you vitex?! Mine refused to give it to me while I was BF...
I had a short LP while BF (10 days) and got a BFP in our 3rd month of good timing (plus 2 months of bad timing). Unfortunately, it was a mm/c, but that had nothing to do with the BF or LP. My LP has been 13 days ever since DD weaned (was 14 days when TTC#1, so didn't quite go back to "normal").

