disclaimer: I do sew professionally, but I also just like to share. I've built a website with lots of sewing gear tips, as a way to sahre, and if I post the link it's for that reason, not to solicit.
I've found the Green Pepper patterns to be wonky in thier sizing. I use the S&S 6 panel short, I hvae to take the waist in but the legs are ok for me... I"m "curvy with a small waist".
For the pad, you might need to experiment. I never ever use the cheap fleece for anything, I just hate it.
for sizing, you might just try cutting your peices with a biger seam allowance so you can adjust. Make sure your fabric has enough stretch and that you are laying out the stretch the correct way: around the body.
here's more tips
penny