IUI with low post wash numbers success (or not) stories

Hey all, I lurk on the sub all the time hoping to be an active participant one day. My husband and I are dealing with hypothyroidism on my end (TSH 1.3 now), pcos (although I ovulate and have regular cycles) and MFI on his end (first semen analysis had good sperm count but low motility at 23%, second had good motility at 34% but low count at 45 million).

I’m having my first IUI with a frozen sample (he won’t be home) after taking Letrozole, and was just informed the sample we’ll be using has 2.2 million sperm... my doctor said this is “adequate” and that they’ve had success with numbers as low as 1 million. But after doing a ton of research, it seems like anything below 5 million is unlikely to be successful.

Has anyone had an IUI with such low numbers? Of so, we’re you successful or not? Did you decide to move to IVF at that point?