I have 3 EE quilts in size “short”, and am just under 5’6″.
All 3 of them are very consistent lengthwise, although they offer different footbox designs: a Revelation X circa 2013, an Enigma of the 2014 vintage, and the 3rd one is a brand new synthetic Prodigy (not yet used in the field).
All fit me very well, with a bit of length to spare – somewhere around 2-3″ get nicely tucked around my neck up to my ears if my campsite happens to be really drafty.
I spend 80% of my sleep time on my side(s), and the other 20% – on my back, fully stretched. Or so I’m told. Stomach sleepers may need a bit of extra quilt length, but if you are one – you will be just fine given your 5’6″ frame.
I have come to realize that when I sleep in a hammock (perhaps 1/3 of my outings), these quilts are actually unnecessarily long, due to my diagonal lay – I use asym. hammocks.
I have no doubts that “short” is the right length for you. Be careful with the width though – base your decision on your intended use, circumference, and sleep habits. Fortunately, EE offers a very decent spread of widths.