I may be wrong, but I think shorty is also allowed as common.
But you are right - these words with both a -y and an -ie ending can be confusing.
There was another example in the bloodiest game, where bootie (diminutive of 'boot') was allowed.
As usual I got it wrong; I played booties first and that got 'sorry, not known'
booty would have been allowed, had the letters been available, but of course with a different meaning.