I think my bird might be egg-bound?

Yes, your budgie could be egg-bound. They act very hormonal, tear up everything, and have messy poops. I've had several chronic egg-laying budgies, and one of them ended up egg bound and died a few months ago. I'm very glad to hear you are going to the vet. The sooner, the better. Have you checked the bird's stomach? It will look all swollen up if she has an egg in her and it will feel very soft. I hope the vet can help your budgie.