Ahoy, Zorinavida!
As you are planning for your trip, I know that luggage limits can be at the forefront of your mind. And, you are traveling a LONG way to take this vacation!
As far as I can find, there is no official weight limit for luggage from Disney Cruise Line. In the cruise contract, it is stated that two pieces of luggage per person are allowed to be brought onto the ship.
In your cruise documents, you are sent two luggage tags per person to put onto your bags for the porters to take. It is not like an airline where they will weigh your luggage, but please keep in mind that real human people have to lift and move your bags many times before they finally arrive to your stateroom. Extra heavy luggage could be damaging to the porters as well as other cruisers' bags if it winds up on top.
There are laundry facilities onboard, which are reasonably priced, so you are able to wash clothing throughout your cruise. I understand that your New York and Canada traveling clothes will be quite different from your cruise clothes. Perhaps you could pack one suitcase per person for the cruise and also one suitcase per person for the colder weather?
If you are bringing medications and/or valuables onboard, you should have them in your carry-on luggage. A carry-on should be about the size you would carry onto a plane. Also, you will have to keep these bags with you until your stateroom is ready, so anything large becomes very cumbersome.
I hope this helps with planning for you amazing vacation. Please come back to the Disney Parks Moms Panel with other questions as they arise.
Happy Cruising, Tracy V.