Hi Katie......

I use Phili whipped cream cheese (which says less than a carb per 2 Tbls) I just figured .5 per 2 Tbls but you could figure it a little more if ya want. I usually just use half the 8 oz container.
Heavy cream I use is Kroger brand which says 0 carbs but I figure it at .6 per Tbls.....I only use 6 T of heavy cream, which is pretty close to a 1/2 cup.
The sour cream brand is Kroger Sour Cream, but the off brand of sour cream at super walmart is the same carb count I believe. 1 carb per 2 Tbls.
Hope this helps.......if not, just ask!!
Vicky