Olive green, overall-style, midi, a-line dress w/pockets, size M but fits like L

Dress from Lighthouse Apparel I bought the dress at a vintage bazaar and was told it was from the 90s but I can’t say for certain. Color: solid olive green Size: labeled medium but fits like a large. Fabric doesn’t stretch too much so it is too tight for my chest (G/H cup) but otherwise fits me (typically size XL) Midi length - 40.5” from neckline to hem A-line skirt - 30.5” wide at bottom High waist - 21” at waist Top: sleeveless, square/straight neckline, overall style (21” pit to pit -> 13” wide at neckline) Centered chest pocket - 7” wide and 6” deep Condition: Used in good condition - no holes, stains, or defects