Don't dragons shed their scales eventually anyway?

Derpy whimpers softly while clinging to Veshora.
"But I'm a tiny soft baby! I don't have scawes yet!"

"Don't worry, little one - I'll help you!" Veshora glances at the pranksters and mumbles something about unneccessary childish behaviour before taking Derpy to the relative safety of acetone and bubble baths.

"Yay! Tank you!" Derpy hugs Veshora and gives them a big cheek smooch. "Mwah!"

Lol whoops! I am a bad dragon mom who has set a bad example of playing pranks...
;>.>

Also, those glasses are insane.

I object! That was absolutely neccessary childish behaviour.

Is derpy ever going to grow?

Depending on the lore you follow, dragons can live anywhere between 150-1,200 human years. As such, it is hard to know exactly how long his infancy stage will last.

As his irl self (from a realistic/ imaginationless viewpoint) is just a plushie, that version of himself will never grow. On Trisphee? Maybe, but that's mostly up to the staff artists and item makers. I artwork? Sure, it would be cool to see Derpy drawn as older in future/later artworks.
But will he age and mature despite his small stature? Of course. Over time.

"Awww tank you!"
Derpy hugs you back, then sits down to play with your kitties.

I don't Derpy to grow and become a scary dragon :<

"No spoopy spoop." Derpy agrees, while giving all of Major's kittens hugs and pets.

Yay!

-hugs Derpy-

"Teeheehee!" Derpy attempts to tickle mdom.

NoOoOoOoo!
teee-heee

"Teehee...Gotcha!" Derpy gives your cheek a big smooch.