Sizing for nikky wool covers?

i found a small nikky wool cover at the secondhand store for $2.99 the other day. score! i'm putting it away for a futre babe. i kind of like the way it looks and i want to love wool but just haven't found the right thing yet. i found one for sale that is an XL that might fit my ds. a website i found says the XL is for 22-26 and he's 25 lbs now. (although with his build he still fits a sugarpea sz1 just fine. how do the sizing on the covers seem to run in your experience? on the small side or large? and do you like the covers?

thanks,
Anne-Marie