Is the Ahmadiyya View of Age of Aisha(ra) wrong?

Introduction:

This article will be divided into three parts. The first part will examine whether it is certain if she was a certain age or not. The second part will review the methodology behind the Ahmadiyya intrepretation of her age. Finally the final part will summarize where the sources of her ages come from.

Part 1:

The nikkah took place but Rukhsatanah did not and she continued to live with her parents. After five years had elapsed (second year of Hijrah), she had fully matured and was the age of 12. It was Hadhrat Abu Bakr(ra) who was her father, that approached the Prophet Muhammad (saw) himself. Some scholars therefore say her age was fourteen and others say sixteen and some even say eighteen nowadays. At the time of Rukhsatanah, it is proven that she was 12 years of age. The migration took place in Rabi-ul-Awwal and for this reason, the first year after migration was night and a half months.

The Rukhsatanah took place in Shawwal 2, so the second year was also night and a half months. Adding these two we get one year and seven months. When we add this to the period prior to migration we get 12 years. So her age during rukhsatanah was 12 years and she was fully matured 

Part 2:

Part 3: