My last period started May 5th or May 6th. I had unprotected sex on May 12th. I took next choice just in case on May 13th. I am on my second pack of birth control and will take my first sugar pill tomorrow. I took a early first response pregnancy test yesterday and it came back negative. Is this an accurate result?

Any time you have sex, protected or unprotected, you run the risk of pregnancy.

There is no way to know if a HPT is accurate. I'd wait a little while and test again.

False negative readings are very common a false positive is rare. So wait, perhaps you will start your period in the next few days, if not, wait one more week and do another pregnancy test