i understand that you're scared. not even a year ago i had my first pregnancy scare, and it was a pretty silly reason but i didn't think so at the time (and after all my time here you would have thought that i'd known better)
it seemed so real to me, i started thinking about it so much and noticing symptoms but took a test, said negative and all of the symptoms went away.
there could have been precum on his fingers, but it's highly unlikely that you would get pregnant from this. stop worrying, i know it sounds hard but stop worryiing so much.
if you're so afraid, then wait a few more weeks and go to walmart and buy a pregnancy test. it's not hard, i've gone by myself twice, nobody judged me, nobody looked at me funny and nobody told my parents, it's easy and itll make you feel better once you've done so & if it says negative then you aren't pregnant. (not true in all cases, but in yours, yes.)