Advice about Progesterone Pills/Cream?

I've seen the cream at GNC. Not sure about the pills. I've read to use the cream from ovulation to your period but when my sister was on the pills (she got them from the doctor) she said she took them from 5-10 says post period every cycle. I just started Vitex (chasteberry) to try to regulate my periods which are anywhere from 35-65 days since I started tracking them. Hoping it helps to shorten and regulate my cycles and have read it can help with ovulation as well. Trying to lose weight too, but I lost 60 pounds a little over a year ago and that never helped regulate my periods before!