Little tip for any budding writers: Whenever you feel the urge to use the word "enormity", use enormousness or magnitude instead. Especially if you're talking about your children.
This is particularly true if you're writing before the 18th century.
Anyone writing in the 21st century however could just ignore the original meaning of the word and go with the meaning it's picked up over time - that is implying a sense of scale without the negative implications. This definition would be supported by a majority of modern dictionaries.
Yeah, that always bugs me too. It seems like a relatively recent thing, too; I feel like I always heard it with the negative connotation growing up and in early adulthood, but within the past 10 years or so I suddenly see people who write as if there were nothing negative about it. It would be like next year seeing people start using words like "terrible" or "PHP application" non-negatively.