Letrozole this month with progesterone of 26 on cycle day 21. So far BFN on 10dpo with bbt dip. Am I out?

This month was the first time using Letrozole 2.5mg after ttc for a while. My blood work on cycle day 21 was 26. I was thrilled knowing I ovulated! On 6/7dpo I had some mild cramping. Wishful thinking, I assumed it could be implantation cramps. However when I took my bbt this morning it took a nose dive and my first response test was a BFN. I was so hopeful this was my month! I had convinced myself I was pregnant. But now I assume any other cramps I have are from declining progesterone levels and AF on the way. Anyone have a similar story with a BFP outcome? I’ve lost my hope entirely for this month :(