Where do I got to see how many items I have in my wardrobe? Is it in the wardrobe itself?

yep! in the wardrobe: https://new.subeta.net/wardrobe/items

i don't think your total number of items is actually visible on the new system, but there are 100 items on each page so just multiply 100 by the number of pages in your wardrobe (well, total number minus one, and then just add however many are on the last page).

Thanks to both of you :) I was hoping there would be a definitive number somewhere but oh well haha

the filled wardrobe achievement will display your highest total number of items in your wardrobe, but the number only ever goes up, not down; so if you've removed things and the count has fallen below that number, it won't be up to date.

there's also the checklist feature on subetalodge, but you have to update it manually (the mass add feature helps but it still takes time) and it doesn't track CWs.