How chubby should my FBTs be?

[JUMPnJACK]

I have two FBTs that I bought about 4 weeks ago? I'm feeding them about a dozen crickets every other day and a couple meal worms as a treat during the week.
They don't seem to be getting any chubbier. They are about 2 inches long and about as wide as my thumb (around an inch).
Should I be feeding them more or is this a good size??? The ones I see online seem bigger....

[adinco]

my frogs took about 2 months to plump up after I got them.