You might be able to call your dentist for advice, without going in for an appointment. This is a short question which might be able to be answered over the telephone. Even if you don't like him, he might be able to answer this quickly, or if he has an assistant, they can give you more information. I know it's really hard to deal with it when stitches aren't going away as quickly as you'd like.
Are you in the UK? There are still hardy foods that you might be able to eat, even if you can't eat a hamburger at the moment. Have you tried Shepherd's Pie? Potatoes, cooked in their jackets, with cheese and other toppings can be very filling. If you can get refried beans, try making a layered rice bowl with rice on the bottom, cooked ground beef if you can have it, refried beans, salsa and/or tomatoes, and cheese and sour cream. This is very hearty and is pretty easy to eat. The ground meat is the hardest thing to chew. Even if you eliminate it, the rest is very filling. Sometimes lasagne can be a good bet, too, or other noodle dishes with sauce. There are hearty soups with beans. Most of these things can be pureed, too, if chewing is too painful. Wishing you good luck - I hope you'll be able to enjoy your hamburger soon.