Welcome to HCM.
You have reached the age of 63 without any problem caused by malabsorption
of fat, then what is there to worry about?.
The doctors have rightly advised you not to worry about it. Most of the present day diseases are directly related to excessive fat intake. You should certainly consider yourself lucky that nature is taking care of you.
As long as you are otherwise healthy, don't let weight and build bother you.
Wish you all the best.