As I understand it the OP isn't ballparking at all. He is simply transferring the exposure of the best test strip to his full print, changing nothing else. He also seems to be working out his test strip exposures correctly and yet if he is doing it all as he says, I cannot work out why his full print exposure isn't right.
Something changes when he does the full print but what this is I now have no idea as he seems to be doing everything right.
I am completely puzzled