Welcome to e health forum.
As you mentioned in the history, that you had sex on day 3 of your cycle, which lies within the safe period of the cycle. In addition, you had taken a emergency contraceptive pill (I pill), which was actually not needed. Anyway by these 2 actions, the chances of pregnancy are absent.
Hence the chances of pregnancy would be very less, since you had sexual intercourse during the safe period of your cycle. In case a woman has a 28 day cycle, the unsafe or fertile days are from day 12 to day 16, during which time ovulation occurs and chances of pregnancy are high. Sex out of this period is safe and with less chances of pregnancy.
Since the tests that you have done, in february were negative, they do confirm that you are not pregnant. Hence there is no need to be worried about the issue anymore.
I hope this helps.