An unprotected sexual intercourse always carries a risk of pregnancy
and transmission of sexually transmitted diseases (STDs).
The chances of you being pregnant are fair.
Pain in the breasts usually occurs due to changes in the female hormones. You should not worry about this and take simple analgesics like Paracetamol
if the pain is severe.
Please wait for your periods to happen, if you miss your periods, do a home urine pregnancy detection test using Velocit Kit or Preganews.
Hope this helps.