Hi Kristina,
Please do not cancel your vacation! You can still have a magical time on vacation!
I know this can be confusing. Part of the issue is that if a child is under 3, they are not eligible for a meal plan because they do not need a ticket. Disney Dining is tied to a park ticket thus why no child under three can have the meal plan.
However, because of safety reasons, Disney needs to account for every guest including the children under three. When I went last year on vacation, I travelled with my 10 month old nephew. All of my dining reservations included him.
Keep trying Disney dining to see if a spot opens up. Be flexible on dates and times. For Tusker House, pick a time range like 1:00 pm to 2:00 pm as this might free up a spot.
If this does not work, try Tusker House for breakfast as this is my favorite breakfast. If it is characters, try another character location.
Crystal Palace and
Cape May Cafe are two great spots.
For Mickey's Backyard Barbecue, try
Whispering Canyon Cafe. This is an indoor, fun and delicious spot. There are pony races and Lincoln Logs to entertain. While you may not have the outdoors, no need to worry about weather. Plus this is my absolute favorite restaurant at Walt Disney World.
Wishing you a magical vacation!
Beth