I go through this with Lady periodically. As your vet said, it's best to just let her tummy rest for 12 hours. If not, she'll just throw again.
Do you have any Pepto-Bismal on hand? You can give her some of that.
Since Maltese are so small, they dehydrate quickly. If you rest her stomach and she is still vomiting, take her to your vet. You don't want her to have to get IV fluids. After the 12 hours is up, you can try to give her a little Pedialite to replace her electrolites. The key is small amounts to see if she can keep it down. A little chicken broth and some rice is good to start with.
I need to start a thread about what all you new Maltese owners need to have on hand/first aid kit!