Any chance you can ovulate on last day of af?

Ttc#2. If I a period naturally, usually they are heavy for 7 days. I haven't had one in a few months so I took progesterone. I got a light 7 day period. On day Cd5 to 9 I took clomid. I noticed ewcm on cd8. I've read the ewcm is how you can tell if u are or going to ovulate. Today is cd 21 and i haven't tried an opk. It's driving me nuts. Yesterday I noticed I had a cramping/pinching pain in vagina. That pain I recognize from last pregnancy but not until 5 months in. Anyway to tell if u ovulated without opk? I want to take a hpt already. Please give any feedback.