Hi Jennifer,
Essentially there is no difference in the "mechanics" of urinating. You use the same sphincter muscle to release a flow from your bladder. The only possible change would be the sensation experienced.
You should be drinking plenty of fluids, particularly to flush the anti biotics from your body. Even with your catheter how much do you urinate per hour and is there any solid particles in it? Is it straw coloured or milky straw colour? If you're not using a catheter bag for inspection, void the capped catheter into a glass container for inspection.
A health bladder should be expelling in excess of a litre an hour, and you shouldn't be feeling any discomfort.
Do not leave their care until YOU are completely satisfied with your ability to urinate, freely, without discomfort and adequate volume based on your liquid intake. You should be drinking at least a litre an hour.
The cocktail of antibiotics, anaesthesia, saline solutions you've been subjected to can cause dehydration to an extent. Hence the need to go over board in flushing fluids.
Hope this clears up quickly for you.
Huggs
Catherine