I haven't been on here properly in the longest time but from what I remember, there were a number of shoots prior to Kate's wedding as well as post wedding where she didn't have anything on yet they still didn't use her. Kate out of all the Angels they signed, was the least known and had the least experience with VS. All the other girls either already had a reputation for their work with VS or had a decent sized following. Trying to promote someone nobody would know or at least recognize as well as having a limited English vocabulary, despite there being opportunities to change that, likely didn't seem worth it for VS.
Eitherway congrats to Jo, it was inevitable that she'd be promoted to an Angel.