A HUGE misconception I've been noticing.
For future reference-
Your height should have no bearing on what size board you choose. What matters are your weight and boot size.
The board does not know how tall you are, nor does it care. What matters is your weight, as the board size will decide how that weight is distributed which affects your snowboarding directly. Your height has nothing to do with this.
The general "chin level" rule is a load of crap.
Weight matters. Boot size matters. Height does not.
And for reference- for park snowboarding, go a bit short. Backcountry, go a bit long.
Boots around size 11-12 (depending on boot) should have a board with a waist width of about 255mm or more. That is where you begin to move into mid-wides and wide boards.