Am I definitely not pregnant?

I finished my last pack of the contraceptive pill in february, had my period the last week of february. it finished on the thursday/friday. on the saturday we had a condom split and got the emergency contraceptive pill roughly 2 hours after. I would have usually got my period last tuesday but i didn't. though i now this is probably because i came off the pill i still worried. i took two pregnancy tests yesterday and they were both negative, though on the information leaflet it said that coming of the contraceptive pill can lead to irregular periods causing me to test too early. i want to get the implant next week, am i definitely not pregnant?