Hi ,
Welcome to the ehealthforum and I am glad to help you out. When pregnancy occurs, cessation of menses occurs. It is true that you have a recent unprotected intercourse history but since you had a period this month, chances of pregnancy become bleak. It is seen that pregnancy only occurs if intercourse occurs within the 6 days prior to and including ovulation.
The best timing of intercourse in order to conceive is day 10, 12, 14 and 16 (in case of late ovulation) of a 28 day cycle. To find out if there is ovulation you can record the basal body temperature( rise around ovulation), cervical discharge( thin and slippery around ovulation) or use an ovulation predictor kit.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For an exact diagnosis, you are advised to consult your doctor. I sincerely hope that helps. Take care.