I had a similar problem to you - long slow labour that ended with forceps and I was unable to pee at all afterwards. I felt the sensation of a full (and painful!) bladder that night but was just unable to go. I told the midwife and she told me to keep trying. When they finally catheterised me, they drained 2 litres which I was told was a very large amount for the bladder to be holding but "fingers crossed it didn't do any damage" 😐
They ended up keeping me in hospital for 4 days with a catheter in, then they took it out to see if I could go. I couldn't, so they sent me home with an indwelling catheter that I had to empty every 3 hours, even through the night. It was honestly the most horrendous thing ever - you're very sore down there anyway, and bleeding heavily, not to mention having to look after a newborn. Urgggh I remember feeling so down and panicking that I'd never get bladder control back.
After a week I had my follow up appointment at the hospital and another test without the catheter, and thank christ I could just about empty my bladder (they gave me a bladder scan after I peed and apparently I retained 98ml, the cut off to me having to keep the catheter in being 100ml so it was close!)
I was advised afterwards to try and go twice each time I went to the loo to make sure I was getting it all out. I practically skipped out of the hospital after that, and I've been fine ever since.
I know it's scary for you, but please try not to panic. Your bladder has been through trama and is having a hard time communicating to your brain that you need to go because of this. It WILL heal in time.
I remember feeling so alone after it because when you google it, urinary retention seems like such a rare problem and there is very little information about it out there. And all the professionals seem to be so vague about it 😣 I'm currently pregnant with baby no 2 and I'm so terrified of the same thing happening again that I'm thinking about begging for an elective c section!
Anyway, I hope yours resolves itself soon x x x