Help! Should i take emergency contraception?


I got my first Depo shot on the 2nd of April. Which was 6 days after my period had began on March 26th, but I wasnt bleeding anymore. On the 4th of April, I had unprotected sex thinking I was protected because I was within the 7 day window of the beginning of my cycle, and my GYN told me if i got the shot within 7 days of the start of my period, i was immediately protected. Should i be concerned??? It is now the 6th and I am wondering if i should take Plan B just to be safe /: Help! @Dr_Paula