Congrats on getting through the surgery, and especially getting past the catheter.
Its mostly two things that affect your bladder and cause it to become more sensitive after surgery…
1. Bladder shrinkage. It is true that the bladder does shrink somewhat after having no expansion and contraction for weeks or months due to the catheter, but it goes away rather quickly. Usually by six weeks or so.
2. Bladder spasms. These cause the majority of the urgency problems, since they often feel exactly like you really have to go. They subside over time, but if you had a suprapubic catheter they might persist for a while. Having an artificial hole in your bladder wall comes with consequences. Your doctor can prescribe medications to help with the spasms, like oxybutynin.
If you’re going after only seconds or minutes, my guess is that you’re having spasms. Are you emptying much when you go again right away?