Both guys have pretty strong chances. Pulling out is not a reliable way to prevent pregnancy. If the guy had recently ejaculated before having sex with you, sperm can take a ride into your body on his pre-ejaculatory fluid; he does not need to ejaculate in your body to get you pregnant. Sperm can live up to 4-6 days in your body so both guys have a chance if you think you ovulated on the 17th or the 18th.
When you do DNA testing to figure this out, test with both guys. Go to a lab whose name you get from the family courts in your area of jurisdiction, and witness the guys doing the swab. Do not do a drugstore test, and do test with both men. Get a lawyer or legal-aid person to help you with getting the guys to the testing, if they are balky. You need to do this legitimately, not ad hoc and at home. You need to go to the kind of lab that requires ID and you need to be sure neither guy sends a substitute in his place. Sorry you are in this boat, but you need to take care of things the real way now.