Hey, have you had a full medical check? Most overweight people have at least one medical problem
High blood pressure, cholesterol, PCOS, insulin resistance, chronic back or joint pain, sleep apnoea, and the list goes on. If you haven't been checked out properly it might be worth doing so.
Also have you checked out any other phi? Some might be more lenient and most will wave the waiting period if you have fully served it with your current insurer.
I guess the other obvious thing to do although not something any of us want to do is.......fatten yourself up a bit more, maybe fluid load before a doc weighs you, wear heavy clothes, etc. I know it sound silly but it might all help to bump your recorded bmi up
Good luck I hope it all works out for you