I am with Larry on both accounts.
I would try to find the tub or shower encloser that does match your drain set up. It would be cheaper to even have it custom made than jackhammering and digging up the floor to match the pipes.
There might be a REAL plumber around that would be able to shed some light on your situation, but in the meantime, I would check into different set up.
© 2016 Renovate Your World LLC