how is the seat width measured? is that like that most narrow or widest part of the seat? are the arm rests about that distance as well or is it more correctly measured with the backrest width? I'm comparing to my current chair (a bit worn) and the seat width measures anywhere from 18-22" I do have some wiggle room but I am slightly worried it may a bit narrow for me but the inner measurements of the arm rests from handle to handle is about 22" which is definitely enough space. The seat width is my only concern all the other measurements are equal to or greater than my current chair most importantly height as my current height is only about 26-27" and I can't properly rest my head all the way back so the extra 5-7" this chair has would be really nice!