Hi Lea, Welcome to HealthcareMagic Forum.
If you have had sex after your last periods, that is June 24th you will have chances of conceiving. Kindly wait for your next Periods, if you happen to miss them, you should get a Urine Pregnancy
test done using a early morning urine sample, which is the ideal sample.
You should be getting yourself examined by a Gynecologist even if the test is Positive or Negative.
To Prevent pregnacy, avoid having sex between the 10th and 20th day of her cycle.
Wish you Good Health.