TTC could I have missed my ovulation window?

Do OPKs only have a one day window? I’m so afraid I must’ve missed the window. My bf and I had sex 3 days ago while opk read no LH but yesterday morning I got a happy face. We didn’t have sex till about 11pm. Did I miss my window? Worried... I’ve been cramping for 2 days now. I tested again this morning and no LH. So confused!