Hot mopped showers are a regional thing (mostly CA). It works, but the quality varies a lot between installers. They don't typically last as long as a conventional pvc liner shower.
There are more than a couple of ways to build a leakproof shower. It doesn't sound like you have one of them.
For shower contruction help, you'll get a lot more help at www.johnbridge.com. Friendly people, and very knowledgeable.
Whatever technique you use to build the shower, the waterproof layer must be on a slope (and the tile is a decorative wear layer, not the waterproofing layer). In a conventional shower, this means a layer of deck mud (a mix of cement and mostly sand) that is sloped to the drain. Then a pvc liner that is clamped to the drain and goes over the curb. Then another layer of deck mud, then thinset and tile. The liner needs to go up about 3" above the top of the curb, so in case the drain gets clogged (or you happen to stand on the drain), it will go out the curb rathe than behind the walls of the shower.
There are other ways to do a successful shower, but all of them have the waterproof layer sloped to the drain.