As a vegetarian I need to supplement with Whey Protein that is from a vegetarian rennet source. I found Jarrow Formulas unflavored whey protein to be excellent. It is fairly inexpensive and has very low sugar / carbs.
One 23g scoop of Jarrow Formulas Whey Protein has:
94 - calories
2g - carbohydrates
1g - sugars
18g - protein
42mg - sodium
Ingredients: 100% ultrafiltered whey protein from milk and lecithin (from soy).
No wheat, gluten, egg, fish, peanuts, tree nuts, artificial flavors, sweeteners.
This may be a good option for you! Best of luck!