Big batch of known likey, no problem

I'm a "flavor chaser", and have 12 mods always going, 12 different flavors. A few are regulars, and they do get mixed in larger batches. The rest either 30 mls or 10, depending on the recipe and how familiar I am with them.
Yes, most flavoring does come in PG, and that will provide a little thinning.
Perhaps to avoid confusion, start thinking in ml/mg, NOT percent. In the realm of nic, it's a magnitude 10 difference!! So your mix will be 6 mg/ml of nic. 6% nic is, uh, 60 mg/ml....
The original recipe was percentages. Maybe I messed up somewhere?
While that's always possible, the numbers you came up with seem to calculate out. Maybe post the original and we can double check? But IF your nic stock is 100 mg/ml, i.e. 10%, the screen grab I posted should get you there, to 6 mg/ml.
The distilled water is to thin the mix. I don't go there, so can't really give any recommendations, but it seems a bit high to me.
Side note, most of us do get (did get? we're stocked!) our nic at 100 mg/ml. Cheaper no matter how much you dilute it. And makes the math easier. PG or VG base is user choice. If looking for max VG, get it in that. I run about 65/35 PG/VG, so get mine in PG.
Personalizing the vape is just another element of vaping that puts it way beyond smoking!