i had my last period on the 30th of may and im on the pill. i stopped taking the pill on the 25th of may for my 7 day break but i forgot to take that last pill and had unprotected sex that day but he pulled out. i had a light period that lasted two days. im suffering with lower back pain, a pain in my right breast, trapped gas in my stomach causing cramps, dierrhea and loss of appetite. could i be pregnant?

Well, it's always a possibility that you might be pregnant, but it doesn't sound like a big chance from what you described.
If you end up being late for your next period go ahead and take a HPT.
Let us know how it goes, ok? Good luck!