There are a lot of names for the heavy cream. Here are some that I know:

whipping cream (comes in a carton or bottle beside the milk section.)
35% cream - refers to the butter fat content.

It is the stuff that you can whip with a beater and it will become thicker and form peaks.

It has 6.6 grams of carbs per cup.

The next best is "table cream" with about 18% butter fat.

Don't buy the stuff in aerosol cans (brands like Reddi-whip) which have sugar added & are much higher in carbs. I wonder if that is what you are using, because the carb count is so high?

Hope this helps.