Best brands for slim children?

[StuntCroissant]

DD (22 months) is long-legged but slim - currently just about into 12-18 month sizes. However everything seems to gape at the waist/fall down.

Can anyone recommend brands which come up smaller round the body? We've tried trousers/leggings from Next, M&S and H&M which all fell down. Zara and Mango were almost ok. Petit Bateau fits her perfectly but is too expensive! Someone told me supermarket brands like Tu by Sainsbury's might be worth a try. Any others?

I have always had the same issue for both my DC's. DD is 7 but often needs age 10 clothes for the length. Polarn O Pyret (Swedish Brand) has always been a good choice. More expensive than the high street but they often have 20% off and have a good resale value on ebay. Other than that, Boden & Gap are pretty good or look out for M&S long / extra long lengths in trousers.

I'll be watching this with interest despite having nothing helpful to add myself! If your dd retains the same shape, you're in for a bit of a holy grail I'm afraid. My Ds is 11 years old on Friday, and is so skinny it's a real nightmare finding trousers that fit. Even high street brands "skinny fit" are way too big on the waist. He does have a pair of shorts which are age 12-18 months which now fit perfectly on the waist, but obviously come halfway up his thighs!
Bought new boxer shorts from Next for him starting Year 6 a few weeks ago - age 2-3. Like I say, it's a nightmare!