I know your pain, literally! I've suffered from severe dryness for 3/4yrs now.
It was also causing cystitis, so ended up having an internal bladder scan just to make sure there was nothing sinister going on, all clear (apart from a fibroid pushing in to my bladder!).
The lovely Pratice Nurse said that being so dry can cause bladder issues, everything needs moisturising! She prescribed 2 x week Vagifem pessary, which has helped 'puff me' up, if you get what I mean! And the bladder issues have resolved.
But I don't find Vagifem brilliant, it works, but I still need something more, tried a few other vaginal moisturisers, but the best one I've discovered is the YES YES vaginal moisturiser - it's non sticky and is supposed to help your body moisturise when it needs it - it is well worth a try, it's the best so far I've found!