Dj's shape-shifting ability's are unfortunately keyed to his emotions so he can't actually control how she changes or when.
When DJ gets to nervous he turns into a dingo. But he also shrinks down and even smaller than his mom and is really scrawny. Here we see him wearing his mothers clothes and you can see how baggy they are on him and his mother was not very tall to begin with. As a dingo he's very skittish and is very easily frighted and spooked.
Art by John Martello