Hmm 750mg each, thats 1500 per day. Not enough.
You need to be taking more than that. Dose recommended is two 300mg or 400mg tablets with each meal (three times a day).
I used to take 2 each mealtime from about 35 weeks. I took 400mg tabs. So took about 2400mg per day.
FWIW my second stage lasted 34 minutes. Natural birth, no medical intervention. I also did perineal massage from about 32 weeks.
Taking them after giving birth is also good. Helps promote healing and stopping bleeding.