What are my chances of being pregnant? I started my period on June 11 and finished the 15. I had unprotected sex the 16, 17, 18, 19, 27 and 28.

Nobody can give you statistical numbers... except that yes it is possible. Far too many unknown variables.

Do you want to be pregnant; that is why you are having unprotected sex so often ?

You may become pregnant the first month of trying, it may take many months, even a year or more. The rough guide is about a 20% chance or so in any given cycle, but there are many factors that come into play besides just timing... hence why it can vary greatly in how likely you are to become pregnant.

See what happens when you expect your next period.