In 1812 the US was much more populous than in 1776. We had three times the population (IIRC) because our doubling time was about 24 years. We were also spread out over the Appalachians, so there would not have been a two front war with the Indians as in the original Revolutionary war. We also had a government with taxing powers that we didn't have in 1776. The conservative personalities that made so many people loyalists were now loyal to the United States. Without quislings on the ground, Britain would have had a more difficult time putting us down.
They could have won the war by splitting us up. New England, the middle states, and the south would all have had different interests. The New England successionists were interested in building a bigger navy that could defend their merchant marine from England. If they split off into a country that was no bigger than the US in 1776 the English might have managed to beat them in a war afterwards since England was no longer fighting France like last time.
The middle states were interested in transport links with the Ohio. New York was about to build it's Erie canal. That's a magnet for Pennsylvania and New Jersey to sign on as a country. They would have insisted that New York break up into pieces, and New York would have agreed if Pennsylvania split tin half too. Maryland might have gone with the south, or with the middle states. I will assume that it went with the south.
The south was interested in Florida. They could have bought it from the Spanish and made it into a state to go with Alabama, Mississippi, Louisiana, Arkansas, Tennessee, Kentucky, and Missouri. The south would be as big as the middle states and New England. No civil war, either. Might be an argument about West Virginia, maybe.
If Napoleon had put off his return for a few more years he might have won. Wait for more soldiers to grow up and be ready to die in battle? Wait for the Ancien Regime in France to annoy more people? Say, in 1820 he lands on the beach and marches on Paris. There would be lots more support this time.
So there are three Americas, one Canada, and England is faced by Napoleon one last time. That would be an interesting timeline.