I don't see how you can eat less carbs being mostly vegetarian. I think the Primal Blueprint is designed for people that really like meat and in previous lives would pair it with grains (rice, pasta, bread) and are now replacing that with veggies.
that's MY story, I know I generalized but I'm assuming it's the case for at least a couple other folks.
Ease into eating meat, it will help keep you full so you'll naturally eat less. I tried living off mostly veggies for a while (still with grains and some meat) and I found it very challenging and I would be hungry a lot as well. I bet also that my carbs were high, and I didn't lose any weight at all.
I used to seriously post here, now I prefer to troll.