If you had conceived during the unprotected intercourse
, you would get a positive pregnancy
test 3weeks later at the earliest. If you have not attained your period so far, you may go for a blood test
and a trans-vaginal sonogram and see a specialist for further evaluation as your ovulation time cannot be predicted exactly due to irregularity of your periods. You may also need to take treatment for gastritis
if it turns out that you are not pregnant. Wish you good health.