Can't Eat Recommended Amt of Calories (South Beach)

I was planning on going with the paid version of the South Beach Diet due to my hectic work schedule. I'm a Network Engineer for a regional ISP - I have an office but rarely see it and may drive 200 miles on a calm day.

I don't like the idea of auto shipping programs as I've been burnt in the past trying to cancel them. I ended up creating my own version of SBD. I just looked at the foods it sells/ships and created my own recipes based on them (love cooking anyways). I'm pretty competent on what's allowed and what isn't on the SBD. When I cook a new dish I make 4 servings or so as a meal prep thing so I can stay on track while I'm on the road.

I started using MFP again to log my intakes and exercise. I've added my recipes with absolute precision - I weigh solids and measure everything besides tiny amounts of seasonings.

I feel like my portion sizes are slightly larger than that on the paid SBD plans. I feel full all day and have way more energy than before.

After I finish the day's food diary I will be anywhere between 500-1000 calories lower than what MFP recommends. It want's me to eat 1,750 calories per day. I'm averaging 20g carbs per day (not sure if MFP is showing me net carbs or total). I'm on Phase 1 of SBD - 4 days into it and planning on staying on Phase 1 for 4 weeks. I've water fasted for up to 30 days before so I'm not too concerned about staying in Phase 1 a bit longer than recommended.

My fat intake is right on target according to MFP and my protein total tends to be slightly negative (by 5-15g each day).

I suspect either MFP isn't geared towards low-carb diets, I have too much protein and not enough carbs in my meal preps, or this is just normal for Phase 1 of SBD (added some Phase 2 foods into the diary just to see what would happen - got pretty darn close to the daily goal on MFP). Hopefully someone with a similar experience can give me some advice. I don't want to try to eat more food just for the sake of raising my calories if I'm not hungry.