If it's comfortable and causing you less discomfort than in the past .... then it must be right.
If you want to try other heights, stand on a piece of plywood (or two) to see if there is a difference.
Or try the ironing board on the plywood riser.
Just be sure to stay safe ... not falling off your perch, or the ironing board tipping.
Just a slight difference of 1/2" can make quite a difference .... positively or negatively.
Also, are you consistent in the height of your footwear?
That can throw off all the careful planning .........