I would strongly prefer not to deal with agencies, who in my experience are liars and incompetents who lie to and cheat and rip off both parties.
Personally, I'm not bothered about the second bathroom, so at a push that can go, but the rest is not really possible to drop.
We want a place for the three of us, not to add to an even bigger place. That's too many factors and none of us are 19 anymore.
The "disabled" part will never affect you/a landlord. We are independent and sort out our own needs (living together being a major means, for example).