Of course you can lose weight and have a healthy diet while being a vegan. I have only toyed with veganism-- I have many vegan (and excellent) cookbooks, partly because the dishes go with meat dishes ala kosher style. So I often bring a vegan dish if I'm going to a potluck so those who eat kosher style (like my H) can enjoy it with meat

I think there are lots of reasons to feel good about going vegan so I would encourage you to stick with it. As a diet it is healthy and as a lifestyle it is lighter on the planet than many if not all other diets.