Confused about ovulation date! PLEASE HELP

Sarah • Fri, Oct 23

Hello all!

I'm s little confused as to when I ovulated, I don't BBT but use OPK, the first picture is on Saturday 10/17 (CD18), the second one was taken on Sunday 10/18 (CD19). Which one is the positive? Are they both? And wen did I ovulate? I have no idea what DPO I am, I'm assuming 6??? Your help is very much appreciated!