CD33 and no sign of AF..

Em

So I'm on cd33 yet I usually have a 27/28 day cycle.. and by usual I mean ALWAYS! Had a blood test done around CD21 and was told I didn't ovulate this month 😪 so I'm just super confused as to why AF is nowhere to be seen. I know stress can interfere but I've actually been really chilled this month compared to others so not exactly feeling stressed. I am just so confused.. Should I take a test or would it be a waste of money? Could the blood test be wrong?