Is the pullout method enough? Should I be worried?

I'm not on birth control but had unprotected sex recently. He used the pullout method and came outside of me (on my chest and abdomen). Now I'm starting to worry whether or not there is still a chance I could get pregnant. Just a little background, I'm 19 and have had very irregular periods since they started when I was 13. Irregular meaning often going 3+ months without one. My last period was 5 months ago. I know it's just my irregularity since I've only been sexually active since a month ago and the other times were with condoms. This recent encounter has left me stressed though. I didn't fully wash off afterwards because I had somewhere to go, though I did try wiping myself as best as I could. I did accidentally touch the outside of my labia while using the toilet right after. Now I'm thinking I won't know if I'm pregnant like other women, since I normally don't have my period anyways. Am I worrying too much or should I take the morning after and maybe do a pregnancy test in a couple weeks? We are not in a committed relationship and I'm not ready for a baby. pregnancy is not an option!