If going back to meat is right for you, then go for it.
But wouldn't it be worth having a look at your diet first? There's no reason for you to be low in energy on a veggie or vegan diet.
Are you eating a healthy balance of complex carbs, protein & fats? Or are you relying on ready meals? I know I do sometimes, but some are a lot better than others.
There's a great free American site, nutritional data, that logs all the normal data + all vitamins & minerals. I find it a big help. It is a bit of a faff typing everything in, but it can be a real eye opener.