Confused and feel silly!!

Hi ladies, please can I ask for thoughts on this issue? I recently had my marina coil removed after 5 years due to ill health, I had a normal period and been following it/logging it on here, but the other evening me and my husband had random intercourse (was more passion than planned if that makes sense?) and we didn't use any protection, however we both previously decided we wasn't having any more children and Was going to use protection until I am well enough to have coil back in place, the app says I was 3% fertile that day, could I possibly get pregnant?? Can't switch my brain off and not due on period for another 10 days?? Help!!