You currently have 0 out of a maximum 4 shops and galleries.

Except I have five, and if I click to them from the commerce tab, I can see and visit all five of them...! :(

edit: It says my shops don't belong to me. I changed my name the last time I played... :) Any chance someone can help me out <3

The shop system was changed completely about a month ago, you'll need to make new shops and move your items. There's a guide thread located here:

New Shop Guides

There's also a link on the front News page, just click on the green piggy. c:

Edit: Oh wait, just reread your post. If you can't actually access the items in your legacy (old) shops from the Commerce tab, maybe file a ticket, that sounds odd.

The shop system was revamped. This thread should help you out. https://subeta.net/forums.php/read/854270/New-Shop-Guides