It seems like the account worth part of the site is long gone and I've already reached the 15k wardrobe items achievement so I can't rely on the achievements counter either.
Is there any other automatic way to know?

You can always do simple math. Go into the old wardrobe, set to forty items per page, then multiply 40 x Second to last page #, then add the items on the last page. For example, say you set the item count to 40 and you have 464 pages. You do 40x463=18520, then count the items on page 464 to add to that number.
Then there is also Subetalodge.org! It may take some time to import your wardrobe to it (the instructs aare very simple!), but I find it a HUGE help to keep track of my wardrobe and whats in it so I'm not buying dups.
If there is any other way to do this I do not know of, but those two are the ways I use.