question about brown (L) v. green (XL) gmd prefolds

2010mommy!

my little girl is FINALLY outgrowing her red (medium) gmd prefolds. if you can believe it, she is 25-months-old and 27 pounds now, and she's been in these reds since she was not quite 8-months-old. crazy, i know!

anyway, i am hoping this next purchase of gmd prefolds are my last before she is potty trained. should i move to the large brown edges, or skip those and move to the green XLs? or, i also noticed that the organic versions of the brown prefolds are slightly larger than the non-organic versions, so maybe that would be a good compromise?

any help would be appreciated! we use thirsties duo wraps, if that makes any difference.