4 cups of fresh mushrooms is equal to one block, so if you started out with that much and it reduced to 1 cup, then you are probably on the right track.
According to www.nutritiondata.com, 1 tbsp of worcestershire sauce has about 3g of carb. So, if you used more than that, it could have an impact on how well the meal was tolerated. 3 tbsp would be equal to 1 block of carb.
I use it often when I cook, but I don't use more than a tbsp--although, I don't measure it, I just give the bottle a few shakes--but I doubt that it amounts to much.