oh the dilemma I wasn't expecting

Now that Becky is starting to TT nicely, most of our pants are too big for her tiny tush

We still have about 3-4 pairs size 1 leggings that fit her but I have given away lots of small pants to St. Vinnies a while ago
Bonds size 1 leggings fit quite nicely over undies but the length is a tad short. Some size 2 Target leggings fit but not as nice, the length is good though. Anyway, just to give you an idea what fits and what doesn't
I can't sew so can't add an elastic to the pants we have

Legwarmers aren't an option either because Becky doesn't like them.
Can someone please suggest what brands/types of pants will solve this problem? I bought a 2nd handed Pumpkin Patch size 2 jeans off ebay thinking they should be small cut, but my goodness they're huge!

Won't even fit over cloth nappies!