Welcome to HCM,
In a regular menstrual cycle of 28 days, ovulation generally occurs on the 14th day of menstrual period.
21st July was your 15th day. Thus the body ache
and slight breast tenderness was due to ovulation.
One can become pregnant due to intercourse done on or around the day of ovulation. You can conceive due to sex if you had on 12th day of period.
Ideally you should do pregnancy
test about a week after due date of period.
As result of urine test is slightly +ve only, you should get blood test
for pregnancy done, and take decision according to report.
Thanks for trusting Healthcaremagic and posting your query.
Hope you found my response to your query informative and helpful.
With good wishes,
Dr.Chandra Shekhar Sharma