29-30 day cycle

Letrozole CD3-7

Positive OPK CD16

Sex CD16, 17, 18 (not rough!)

Brown spotting CD 18, 19 and 20 (today)

I used pre-seed for the first time, I was careful inserting the syringe thing. I've never had mid cycle spotting or bleeding of any kind. I know its way too early for implantation bleeding. My midwife friend said ovulation bleeding is extremely rare and it's most likely my period starting. I'm not so certain, the letrozole keeps me to a 29-30 day cycle...

Has anyone experienced spotting mid cycle? Or spotting after using pre-seed? Is this normal? I hate to ask and get my hopes up - but did spotting result in a BFP?

Thank you for taking the time to read this, and thanks in advance for any responses.