An even larger export was cotton, and by your logic all that cotton should have been exported from New York or Boston because that's where all your ships were turning around and heading back to Europe. But in fact only a fraction of the cotton was exported from New York and Boston, the overwhelming majority was exported from Southern ports. So if all those goods were destined for Southern consumers anyway, as you claim, then why didn't they take them direct to the buyers? Why did they stop and drop them off in New York before heading down to load with cotton?
The fact is that the goods landed in Northern ports because that's where the consumers were. They did not land in Southern ports because the demand for the goods wasn't there.
You said: “The fact is that the goods landed in Northern ports because that’s where the consumers were. They did not land in Southern ports because the demand for the goods wasn’t there.”
One of the major major British exports to America — if not the biggest — was machinery, and the Southern states were the biggest customer. The Northern interests would not import something that they made themselves. One of the reasons the tariff was created was in an effort to force the South to buy its needed machinery from the North, when they (the South) had a far better deal obtaining those goods from Britain, and the South had commodities Britain desired to make the trade balance profitable for both. However, that “cut out” Northern industrial interests, which was something the North could not abide, so it introduced prohibitive (for the the South) protective laws.