Does ovulation ensures secretion of progesterone, for uterine thickening?

I m a 27 years old woman,m looking forward to concieve,I missed my periods for last two months,doctor said, follicles were too small,he gave me proper treatment for making follicle size big and then hcg injection for ovulation, and I took ultrasound too for making sure of ovulation, me and my husband also had on the required days, but I ve heard that sometimes , ovule after fertilisation doesnt attached to uterine wall, should I go for progesterone injection to come in safer side or ovulation itself ensures that progesterone will be released.Please guide?