IUI and follicle size

What’s the smallest sized follicle you’ve gotten pregnant with an IUI on?

This cycle was very frustrating. Between different meds and such and making a long story short my lining was great and my blood work showed an LH surge on its own, but my follicles were not great in size, I think one was 14 or 15mm and that was the biggest. My IUI’s are covered now that I’ve met my deductible so I had the option of intercourse or IUI and we chose IUI solely because it’s covered and if there any possible chance I’d rather give it a better chance with IUI. I’m doubtful this cycle but hey, strange things happen lol.