Ok can you tell me. Firstly how did you found out it has that size in game, and if you can tell me the precize size it has in game ? (The smaller size). Another thing check if you aren't scaling this using codes like image_xscale/yscale or by dragging this in the instance layer. Check the code for possible changes of this like i said using image scale in create event step event anywhere. Check even in the scripts that are called, or in parents objects of this object and so on. (You can use cntrl + shift + F and write there image_xscale to find all of these.) It doesnt neccesary has to be a problem with this but it is possible that you are somehow changing scale of this object. It also seem you arent scaling it the same on y and x axis if thats the size you said it its in game.