If you don't have a problem with soy products then the veggie meats (although you have to watch the labels for ingredients) are high in protein, low in carbs and calories.

I typed a typical veggie day for me prior to being pregnant but added a chicken breast for the evening meal just to see what it might be for you subbing 2 veggie meals and this is what it came out to....

Calories Eaten Today
source grams cals %total
Total: 1202
Fat: 71 643 56%
Sat: 27 244 21%
Poly: 7 64 6%
Mono: 22 201 18%
Carbs: 41 97 8%
Fiber: 17 0 0%
Protein: 101 405 35%
Alcohol: 0 0 0
((24 net carbs for the day))

meals were as follows:
Breakfast:
1 soy sausage patty
2 egg whites fried in 1/2 TBL butter
2 cups cabbage just wilted in a hot skilled (or use pam)
1/2 cup of strawberry slices

Lunch:
8 med asparagus spears sauteed in 1/2 TBL butter
1 better than burger with a 1oz slice of muenster cheese melted over top
2 thick slices (1/2" of tomato) topped with 1 TBL Ken's Northern Italian dressing

Dinner:
1 small chicken breast (skin on) coated in 1/2 TBL olive oil, salt, pepper a shake of basil and 1 TBL shredded parmesan cheese
salad with 2 cups of romain lettuce, 1 hard boiled egg, 1 red pepper ring (1/4" thick) and 1 TBL of ken's northern italian dressing

Cup of herbal tea with 1 oz of heavy cream

I just don't see how people eating meat stay low calorie/ low-carb. The small chicken breast with skin was 330 calories. That was so much more than any other thing I typed in. Anyways goodluck trying to figure it out!

Jenn