Trying to decide which day I may have ovulated...

Ovulation occurs anywhere 24-36 hours after your peak so it's quite likely you would have ovulated on CD18 OR 19.
Some women like to temp check throughout the month to help them pin point the exact day but that's a whole different kettle of fish I hated it and it only really tells you for certain after you've already ovulated.

 

It sad when you hope it finally happened and then you get negative results and Af

But that life we can't to anything about it.

 

sperm can survive for up to 5 days once safely deposited. Me and my OH DTD 2 days prior to my OV date this time and actually just the once as after a year of trying I'd kind of given up.
A lot of women like to cover their fertile period or when they start to get their dark lines on opks by having sex every other day until you start getting negative OPKs. I hope your TTC journey is short and I'm sorry to hear of your recent miscarriage. Please don't be too disheartened if you don't have any good news this month as our bodies can take a little while to readjust after a loss but everyone is different. Try and stay as relaxed as possible easier said than done I know. Good luck