I've liked
Matilda ever since I read the book, too. It's a warm and cozy kind of name.
Tilly and
Maudie are my favourite nicknames.
From your combos, I like
Matilda Erin best.
Here are a few more suggestions:
Matilda IvyMatilda VioletMatilda CloverMatilda Rosemary
Hmm. For some reason I keep wanting to pair it with a plant-related MN.
Matilda FrancesMatilda JaneMatilda EveMatilda VerityMatilda WrenMatilda BelleMatilda Lucy