Nervous wreck

My partner and I had unprotected sex a little over a week ago. He pulled out, but cum was still around my vagina. I didn't really think much of it because I wiped it off and cleaned up. Someone asked me if I was pregnant today (after I mentioned I was having really bad body aches and was super tired) and I laughed. Now it's really got me anxious and worried....what is the likelihood of a pregnancy occurring if the sperm wasn't directly in the vagina?!?!? I already have 2 children, but they were both planned. I've never had to deal with this!!!! Help!