Ouch.. I understand if the artist would be overwhelmed by owed works, but it don't seem like that seeing they still take on new requests and commissions. Maybe she just got disinterested. Not that it's an excuse of course, and it's incredibly bad form to you ignore you, just thought that could be a reason as why she was late to start with.

Have you tried messaging her in the emal she refers to for requestests? Requests?*