It really is a shame that you have to deal with this. You may in fact want to look into the underpants designed for cis women with that sort of problem; it's embarrassing, but as a backup plan it might work. There are also surgeries on the bladder rather than the urethra to help with bladder control, though for that, again, a surgeon who specializes in fixing cis women might be better than someone who focuses on GRS. (Hysterectomy is one reason why women develop bladder control issues, so such surgeons would be used to working on women without a uterus.)
As for the urethral dilation, it does sound like your GRS surgeon should have taken your concerns more seriously... it's odd that a surgery which only affected the last bit of the urethra (and the part that's gone, obviously!) should have caused a stricture the whole length of the urethra, but clearly it has.