Thanks for the query.
If you had unprotected intercourse
around the time of ovulation, there is possibility of pregnancy.
Menstrual bleed can get alter due to many causes, so the spotting you had could be hypomenorrhea
Sometimes urine pregnancy test kits may not give accurate results in early pregnancy.
So you once go for blood test
for pregnancy or ultrasound
, which can give more accurate result compared with urine test.
For more details you can ask me through: http://www.healthcaremagic.com/doctors/dr-sree-gouri-sr/63429