As you said it is extremely early to determine whether you are
pregnant or not. As you had unprotected sex with natural methods of birth control, chances of failure of this method is very likely. Moreover your ovulation timing corresponds with the exact time of the unprotected coitus. So just wait for your periods during the expected time. If you miss this cycle get a home urine
pregnancy test and consult your gynaecologist. Regarding cramps these can be either pre menstrual or implantation pain.