For Canada, either the US is successful in invading, and securing the Quebeckers' help, and Jonathan Eddy is successful in getting help from Washington, or the US successfully invades in 1812 and holds the land (less likely to me).
For Cuba, President Polk buys it in 1840 or so from Spain, but you may have to either have some kind of rebellion or crop failure there, or somehow make it more advantageous for Spain to drop it than keep it.
For Jamaica, maybe during the War of 1812, but it's unlikely the British would give that and the Cayman Islands up without a fight.
For Hispaniola, the Dominican Republic asked to be annexed in the latter 19th century. That would need to succeed, but it's not a highly likely event.
For Mexico, you'd need a more zealous ambassador after the Mexican-American War, which is possible, but I doubt the Americans would want so many people who don't speak English in the country at this point, and ditto along Central America. Central America had in the 19th century just thrown off Spain's control - why bring themselves under the control of people who don't even speak their language, and don't share their faith?
Some parts are more likely than others, definitely. It's just my opinion, but the most likely 'larger USA' would be the "our timeline USA" plus the Republic of the Rio Grande, perhaps the upper tier OTL Mexican states (Baja, Chihuahua, Sonora) since they were then so sparsely populated, more/most/or all of British Columbia. From there, slightly less likely would be Rupert's Land, Cuba, and Puerto Rico to become states, then Hispaniola, Canada, Jamaica, and least likely would be Central America and all-Mexico.
