BFP after MC

Well I’m assuming it’s a yes, I’ve had 3 positives in a row but have no idea how to figure out my dpo... (first pregnancy) and I cannot figure it out, but in the mean time I’ll spread some positives your way!!! Praying for this pregnancy to be healthy! (All three different brands) if anybody can walk me through on how to count my dpo I would greatly appreciate it!!!