Going vegan straight from a regular Western diet, with no vegetarian phase, sounds like an experiment that is almost guaranteed to cause problems like the one you're facing. Why not see how vegetarian works for you for awhile?

Or better yet, why not have meatless days every day of the week except one, when you allow yourself a small serving of something lean and healthy. It may be enough to keep the cravings at bay. Then, drop the meat completely when you think you're ready.

I don't want to sound like I'm throwing cold water on your dreams, and kudos to you for tackling this. You can definitely do it! But for you to have success, you want to think about the long-term. Gradual changes are more likely to stick than abrupt ones.