Decal sounds fancier but by definition, most of us are sticker makers. Just embrace it, nobody will think less of you.
Definition of decal
: a picture, design, or label made to be transferred (as to glass) from specially prepared paper
Definition of sticker
1 : one that pierces with a point
2a : one that adheres or causes adhesion
b : a slip of paper with adhesive back that can be fastened to a surface
A dictionary is descriptive, not definitive. There are no definitions in a dictionary, only descriptions of word usage that were in vogue at the time the volume was published. If argumentum ad dictionary isn't a formal fallacy it ought to be.