How can I see how many items are currently in my wardrobe?

So far I can only find the achievement count, but since this number doesn't decrease when you remove items from your wardrobe, it is probably not accurate right now.

There's sadly no way to find an accurate count that keeps up with removals by itself.

You could register on SubetaLodge and create a Wardrobe checklist, but you'd have to manual edit it as well if you remove items. But it's more practical than what Subeta has to offer.

I've always just done (the number of pages - 1) x the number of items on each page, then count the last page and add them. So like if I have 40 items per page and I have 17 pages, then I have (16x40) + however many's left over on the last page.

It's not particularly efficient, but it's a lot quicker than Subetalodge.

Same, I usually do what suggested above.