I had that problem with dd when she was 5. I was SO frustrated. Somehow we muddled through, mostly by rolling up the legs, and cinching the waists of larger pants. I bought her a pair of boy's jeans that she loved. She wanted to wear all boy's pants after that. I did get her a couple of pair of boy jean shorts over the summer, too. They are just so much more comfortable. I got the jeans at Kohl's, Levi's, I think. And the shorts were the $3-$5 kind from Walmart.
She mostly wore two dresses with leggings from gymboree last year. I got them both from ebay.
I was very, very pleased to discover this year (at 6), she has lengthened, but not gotten bigger around, and all the stuff I bought last year fits her SO cute this year. (She never was chubby, even, btw.)
And, oddly enough...I noticed that ds, who is 4.5, is chunking up in much the same way dd did. Maybe it's a 4-5 yo thing. :)
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