Extension for leave to remain under 352a and Article 8

I was granted leave to remain in UK from June 2014 to jan 2016 which is total 20 months under 352a and article 8 after the refusal of my asylum. I got this leave because my wife was in UK she came to UK after me but her asylum case was accepted before my hearing and she is on refugee leave to remain until 2018.

Now my extension is due and I am a bit confused in which category do I need to apply for leave and also I heard that home office has issued me less period of leave to remain which should have been either until 2018 as my wife or for 24- 30 months.

I would really appreciate if someone can help me and give me better understanding of this