Bladder....lack of it.... post op...help!

I had a vaginal hysterectomy and secoundary prolapse op on Oct 27th 2015. I know its only been three weeks and initially I thought I was doing fantastic and wondered what the fuss was about! However I am finding it more uncomfortable to sit down directly onto my foo 😉 like a bruised sensation and began suffering inconvenience but strangely not until post op of two weeks, whys this? I was warned when they go down the list of side effects that due to the bladders new sitting position some women find it a little sensitive and some women find they get uti for a while after but I am like a watering can and using a sanitary pad in case I don't make it to loo in time, often pre tinkling!!!. I'm best to mention I'm on a tablet here in the uk called vasacase which is for an overactive bladder since having my whooping and damaging 9lb baby vaginally. But apart from the feeling I need a huge wee when I don't that part of my bladder has never been an issue in day to day life. Has anyone else had delayed bladder probs that have transpired whilst they were on the mend.