WoW that's hard to look at! Nothing personal, I've done the same thing
Here are some reasons why it turned out this way:
>Pics were taken horizontally, therefore take up more space
>Template format has text on the left, making everything wider
Most templates will not accomadate this kind of setup...your best bet would be to do everything vertically, pics on top, text on bottom.
I saved the instructions since I just did the same thing myself
1) Locate your listing in your Saved Listings folder, make any necessary changes, and save.
2)Check the box next to your updated listing in your Saved Listings folder and click the “Get html” button.
3) Copy the html in the popup box.
4) Locate the item on eBay and click the "Revise Item" button.
5) Click "Edit Description" then click the "Enter your own html" tab.
6) Paste the copied html in place of what's there and save your changes.
The only problem when I did this was I lost the scrolling gallery, but everything else turned out fine.
Good luck!