You acknowledge that the overwhelming majority of AJK's population descends from tribes that migrated from Punjab and that many speak languages such as Pahari, Potohari, Hindko, or Punjabi rather than Kashmiri. Yet you reject any Punjabi connection while simultaneously claiming a Kashmiri identity.
The Afghanistan comparison does not work because "Afghan" evolved into a national identity encompassing multiple ethnic groups. "Kashmiri," however, has traditionally referred to an ethnic and linguistic group originating from the Kashmir Valley. If ethnicity matters, then ancestry, language, and historical origin cannot simply be ignored.
You also portray the Sikh Empire as a Punjabi force opposed by AJK. But Sikhs themselves are Punjabis. Ranjit Singh's empire was fundamentally a Punjabi-led state, and many of the groups that later became part of Pakistan's Punjab, Jammu, and AJK were incorporated into it. Fighting the Sikh Empire does not somehow make a population non-Punjabi.
Nobody denies that people living along the LoC have suffered from Indian shelling and cross-border conflict. However, suffering does not determine ethnicity. The question of who is ethnically Kashmiri is separate from the question of who has suffered because of the Kashmir dispute.
If the basis for being Kashmiri is political affiliation rather than ethnicity, language, ancestry, or geography, then the term loses any clear meaning. By that logic, millions of non-Kashmiris who support the Kashmir cause could also claim to be Kashmiris.