Naomi looked 10 by the time she was 5, so might have likely looked 20 by the time she was 10.
Kim could have been a problem.
All that growing would have required a massive amount of energy.
1. Naomi slept twice as long/Napped much more often than human children.
2. Naomi was always eating, which is why she was always in the mess and always with Neelix.
(3.) A little of column A, a little of Column B.