It seems like the problem starts at the subfloor. The contractor who fixed the subfloor should have done it in a way so that the subfloor wasn't an inch lower on one side.

We are in the process of interviewing several potential contractors. After these screening interviews, we will ask for bids from the 2 or 3 contractors who are most knowledgeable and compatible with us and our project. We know what we want for most parts of this bathroom, but we are still trying to understand the best way to design an accessible shower. We want to add it now as we rework our main floor so that we can eventually "age in place". The four contractors we have spoken to so far have looked at the joists, sub-floor and open access from below; and all confirm that we can readily recess the floor under the shower. They differ, however, in how they would handle the shower pan and drain for this curbless accessible shower. A couple of them have suggested the Wedi system with a linear drain. Another talked about the Schluter system, and a fourth contractor said his tile man only does a traditional mud base with a central drain. They all said that floor in the main part of the bathroom could be level and the sloping would all occur within the 4' x 4' shower (1/4" per foot). Most would put waterproofing under the whole floor, but one typically extends the waterproofing just a foot or two beyond the shower entrance. Are there reasons to go with the traditional mud base vs the Wedi (or other foam type backer)?

Jacuzzi makes a Tru-Level shower base - we've had one for years in our MB (with tile on the walls), and will be putting one in downstairs as well. It's held up beautifully, feels very solid, and cleans like a dream. We bought our original one at Home Depot Expo, but were at Lowes this weekend and couldn't find one on the floor. We did find a Jacuzzi catalog, however, so it's probably a special order. Here is a link that might be useful: Jacuzzi tru level shower base

A picture would help :)