Hi John, sounds like you were nearly there.The common size of a catheter is 12 and these days are self lubricating .From what you say it sounds like your sphincter is all tensed up and is rejecting the catheter .Try it again and when you get to the sphincter try and relax your body,think of nice things and gently push the catheter through the sphincter.Easy for me to say that but I have had those problems in the past

Just to add to what I said before John if you get the catheter up to the sphincter try coughing and push.Coughing momentarily relaxes the sphincter