Is my lawyer supposed to pay me back for an injury?

It depends on many things....liability for openers. Slip & fall cases are very difficult to prove liability in many instances, as you have to prove the landowners knew or should have known of the condition that caused your slip and fall, and the condition that caused your slip & fall should not have been easily observable by you. That's a tough burden. I would be willing to bet that your lawyer argued for all of the medical bills, lost wages and pain & suffering, but the insurance company probably argued you wouldn't win the trial, so your case got resolved somewhere between the best value of the case and losing the case altogether.