Unprotected sex

I have a 4 day cycle. My and my partner had sex the day AFTER I finished my period. We used the withdrawal method as protection, we both know for certain he did not ejaculate inside me, but there was a slim chance of pre cum going inside me. My chances are very slim of becoming pregnant as I had just finished my period and he pulled out way before ejaculating but with a slim chance of pre cum.

Would you suggest I take a morning after pill?