FSH levels… big drop?

Hi helpful ladies!! I’m having my third

IUI this week. I had an 18mm follicle today (Monday) and doctor wants to do the

IUI on Thursday after seeing blood results. I know a high FSH is not good, and last month during my period it was at 10.08. This month during my period it was 6.28 (The only times they tested FSH during my cycle). I’m cautiously optimistic… should

I be??? Why is my FSH so much lower this month? Is this big drop good? If anyone could explain it would be GREATLY appreciated!! Thank you in advance!! Baby dust and prayers to all!