DPI stands for "dots per inch", which lets you know what the pic's resolution is going to be. It is not a file type like JPGs (I understand that) BUT a 300 DPI image is going to take quite a bit more space than a 72 DPI pic because there is a lot more info in the file. ...
I still believe its a resolution issue, ... obviously you are trying to save the detail in your image,
take your "original image" and save it at what ever size it is. then reopen the image from the saved file in another project (without dragging the scale) just open the image as is, when the image opens , Im going to assume it will be quite large.
Now down scale the image to the size you want and save it at 96 DPI in a web safe format like PNG, these are a bit larger but it will maintain transparency if you have any.
load your image into C2 and you should be ok...
also in the future, when your drawing images make your canvas size roughly the size you need for your image so you stay within the boundaries, I guessing you have a full sheet around 900x600 that your drawing a image on and that is where your problem is coming into play. "but I could be wrong" no insult intended... I myself have made mistakes like this and it turned out to be that the draw software was scaling the image back to original size on save to preserve the DPI.