I've created a PNG version of a document that I made in Illustrator. The PNG seems to have a couple inches of white space next to it. I have checked for artifacts to the side of the doc. Nothing I don't have any hidden bounding boxes or clipping mask's overhanging my artboard. I even created a new blank document and carefully copied the body of the work and pasted it into the new document. The space is still there in the new PNG. What could be going on that i've missed?
Change to View > Outline Mode. Do you see anything as outlined?
What happens if you Select All; open Artboard Options; change the Preset to Fit to Selected Art? Then try Export > Save for Web (not the usual Save or Save As).
Using "Clip to art board" in the save dialogue will let you determine the size and bounds of your image. Sometimes a shadow blur will extend your artwork dimensions even if you can't see it.
I just had the same problem and figured out it was the bleed. Go to "File > Document Setup" and make sure the bleed is 0 for all sides.
When exporting as PNG make sure you check the box which says "Use Artboards"
I also had the same issue. I had a large image masked inside a smaller frame in which the masked part of the image was being included in the final size during export. Selecting the "Use Artboards" option during exporting corrected the extra white space issue.