90 grams of carbs is still not all that high. I don't have kids so I don't know this, but ISTM that breast feeding requires energy just as if you were exercising. Mark's carb curve allows up to 150g, doesn't it? You could probably eat more carbs and be fine as long as you avoid the bad oils and the wheat and corn. If you want to find your limit, you could carb up until you gain a little weight, and then stay below that level.
You know, lately I've been binging on sugar -- quite badly, in fact. Yet I don't seem to be gaining any weight. Or, it seems that the exact moment I gain a pound, I just get tired of the sugar and go back to eating primally again and lose the pound. The up and down cycle takes about a week. I can't figure out what's going on.
5'0" female, 45 years old. Started Primal October 31, 2011, at a skinny fat 111.5 lbs. Low weight: 99.5 lb on a fast. Gained back to 115(!) on SAD chocolate, potato chips, and stress. Currently 111.