For a healthy, couple where both partners are under the age of 35, the chance of conception is estimated to be around 25-30 percent per month, if you have regular unprotected sex around the time of ovulation.
Ovulation occurs on 14th day of cycle in a women with 28 days cycle. It may vary if your cycle length is different.
Chances of pregnancy
further decrease if you are not careful about your fertile days ( it may drop to 11%) in such cases.
Moreover after stopping certain hormonal
methods of birth control it may take few months for your fertility
to return to normal levels.
The pain you are having may represent ovulation. If it increases in severity or is bothering you, you must visit a doctor for evaluation.
I hope I answered your question. Take care.