♡Baby "I'm the little bro" one piece

Measurements/details are in pictures are from the front of the onsie to the buttons & the other is from armpit to armpit. The size is labeled 80 in European size & in centimeters. Normally means it's a 12-24 month (20-27lbs) & 28-32 inches. But I think it shrunk a lot & now is much smaller. I'm assuming it's current size now is 6-9 months in size because it matches another onsie of that same size. Worn only a few times. Well taken care of. All black (not faded) with white imprint ("I'm the lil bro") wording on front, nothing on backside, snap buttons, short sleeve & medium weight stretchy material.