Luteal phase length and breastfeeding

I am almost 2 years PP, but did quite a lot of breastfeeding until DD was 18 months. I have been slowly weaning (I'm prone to mastitis) the last 6 months and got ovulation pain followed by AF a couple weeks later in April. DD was down to twice a day by then. My LP was around 9 or 10 days the first two cycles, then 14 days when DD was down to once a day. Now I'm at once every other day but LP last cycle was back down to 10. (I O'd at the usual time but got my period early.) I had an IUI on Monday, but I'm nervous that my breastfeeding might interfere with a sticky baby. They say your LP should be more consistent than your FP, but I find the opposite is true with me. Could BFing be the cause?