I wear an 18/20 quit smoking and put on 20 lbs in a couple of months so went up a size.  now I roll the waist.  I should have stayed with the 1x
The fabric and quality are nice.  Very comfortable since I got the pj size!  But I think they would have been in the smaller size too.  So if your on the fence, I'd say stay true to what you've been wearing, no need to go up if you just need a couple of inches.