My house was built in 1976, I am the original owner. This is a single story slab frame house. The bathroom off the master bedroom has a fiberglass shower. The bottom of the shower has started to sink in toward the drain in the middle of the shower. Now there are actual tears in the shower floor and cracks along the sides at the bottom of the shower.

I read an article that suggested drilling a small hole and spraying foam insulation under the shower to give it more support. When I drilled the hole I found the shower is sitting on dirt. Apparently over time that dirt has compacted.

This bathroom is extremely small. Only five feet from shower to opposite wall, only three feet from sink to opposite wall.

How do I fix this?

Is it possible to repair with fiberglass repair kit? Or will the slopping floor only continue to tear and create more cracks and tears?