Prior to the recent changes, I had about 2870 posts. Now that number has dropped to about 2450. The posts which I assume are the ones not being counted are still present, but the number doesn't reflect this. They also no longer order themselves properly, such as when I try to order them by the number of favorites or upvotes. Instead, several posts are randomly arranged at the very end of my list.

Yeah. I actually checked my profile and mine says that I have 476 posts. I counted my entire gallery (7 pages total), and my calculator says that I have 517 total uploads, which is what it was before the site layout was changed.

It may take a while in your case, but I'd go through your gallery of posts and calculate each one by row and page just to make sure. Not sure what caused this error, but all of the posts I made that weren't already removed are still intact.