Rasulullah (sallallahu alayhi wasallam) used to perform Salaat in different ways.

Answer

Brother, you are occupying an insignificant stratum in an epoch which is separated from Rasulullah (sallallahu alayhi wasallam) by a chasm of about 14 centuries. The greatest authorities of Islam, viz., the Sahaabah and the Aimmah-e-Mujtahideen of the first era of Islam, have taught this Ummah the Islam which was perfected in the very age of Rasulullah (sallallahu alayhi wasallam). These illustrious authorities imparted to the Ummah the teachings of Islam as they had understood, and the Math-habs have come down to us reliably from great authorities.

These Math-habs are as old as Islam because they are in fact Islam. You and us in this belated age in proximity to Qiyaamah are non-entities which could be equated to morons. You and we possess no licence for digging out from the kutb Hadith narrations, then subjecting the Ahaadith to our personal, wildly fluctuating opinion to formulate masaa-il. Such a methodology will be the inspiration of shaitaan who is adept in the art of deceiving and entrapping Muslims via 'deeni' channels. Our function is only to accept, believe and practise the teachings of Islam as they have reached us from Khairul Quroon (the First three Noblest eras of islam). There is no scope now for fabricating another math-hab for achieving some sort of corrupt unification of math-habs. Allah Ta'ala, in His Infinite Wisdom, has willed the presentation of Islam in the form of the existing Four Math-habs.