Progesterone help

Ash • TTC 8 years - 6 clomid IUI’s - 👼🏻 x 2 - IVF July 2019 w ICSI & PGS - ❄️❄️ FET #1 Oct 2019 BFN - ERA Feb 2020 - FET #2 Sep 2020 BFP!

My MC was in June @ 6 weeks, 5 days.

I just had my 3rd IUI on Monday.

My question is- should I be on progesterone? My RE has never tested that & I’m terrified of losing another pregnancy.

So I’m curious if I should request it.

Also- when is it usually started- after O or after BFP?