IUI with Male factor infertility

Hello, my husband has slight male factor infertility. All the semen analysis parameters are slightly lower than the WHO reference range.

All okay from my side. I ovulate on my own, regular cycles, no blocked tubes, no endometriosis, slight adenomyosis, no fibroids or polyps, no PCOS, taking medication for hypothyroidism. My AMH is 1.25 and AFC 14.

I’m 34F, he is 38M. We have been trying for 16 months using OPKs. Never seen positive pregnancy test.

Is it reasonable we do an IUI next or is it a waste of time? Should we move on directly to IVF?