Given the dates you've outlined, yes, it is possible for you to be pregnant if you had unprotected sex. In fact, if you have an average menstrual cycle of 28-30 days, you would have reached your peak fertility time sometime between 16-19 June. If you do have a regular menstrual cycle, you should expect your period to begin 28-30 days after your last one began - so this would be the first few days of July for you.
1. Take a home pregnancy test.
2. Make an appointment with your doctor or with a pregnancy advice service.
3. Talk to a friend or someone you trust. If you're a young person, this may be a teacher, a parent or perhaps a friend's mother.
Good luck.