Have you been evaluated for a possible urinary tract infection?
So, after the prostate procedure, this was the outcome? Have you been back in touch with your doctor? Is it a feeling of needing to go? There is something called urge incontinence which can happen after treatment. You able to make it to the bathroom? You can also get an irritable bladder after. These are complications to prostate surgery. The problem you are experiencing is, unfortunately, not uncommon after prostate procedures. I would absolutely talk to your doctor to discuss ways to work through this. By the way, you had a catheter? How long was it in place? Talk to your doctor about prostate exercises (a lot like kegel exercises) and pelvic floor exercises. Doing these may help you with any incontinence, as well as the urge to go and frequency.
This is a whole article that mainly does focus on incontinence which you don't necessarily mention but these suggestions may help with overall bladder control and urge to go/frequency as well. https://www.webmd.com/urinary-incontinence-oab/mens-guide/urinary-incontinence#1 It has a treatment section. One thing it talks about is lifestyle things like not drinking very much before bed. And it also has a section on strengthening pelvic floor muscles.
Talk to your doctor though is my best advice.
Not a medical person, but it's possible that your excess weight is pressing on your bladder when you lie down.causing you to feel the need to pee.