No question is ever stupid. I worked in the community setting and often did routine catheter changes. I always found them tricky if the patient had a empty bladder. I often would ask my patient to drink a glass or two of water prior to the catheter change. I also would try to palpate the bladder if I did the catheter change and no urine has returned. This often helps with the urine flow. Lastly I always flushed the catheter and ensured it flushed with no problem and no pain. Also after inserting the catheter I would have the patient walk around for 5–10 mins, often this would help to see if any urine would return. I also felt uneasy and did not like it if there was no urine return because it always questioned me if I was in the right spot. Lastly patient education about returning to the ER, MD etc if no urime return would be a safe bet and just run it by the doctor as well and see if they have any other suggestions.