You are right, I should have educated myself about Southwest's policies, but as I said in my original reply I had only ever flown on small commercial carriers for business up to that point and I thought that's how all airlines operate: you pay for your ticket and are given a seat assignment, show up at the airport with a boarding pass and sit in your assigned seat. I booked the Disney trip through a
travel agent and did not know about Southwest's wonky seating arrangements, had no idea that I needed to print my boarding pass exactly 24 hours in advance of flight time to get preferred seating. I printed the pass the day of our flight (I have done the same thing when traveling for business and it's never been an issue) and so we were assigned to the last seating group, by the time we got on the plane it was mostly full and there were no seats together. The flight attendant was rude and not helpful at all and tried to bully me into sitting far away from my son, so I feel like I have every right to be upset with Southwest, as that is the company she was representing.
They didn't force us to be separated, but the flight attendant implied that we would have to separate or get off the plane (as I said we were in the last group to be seated, so they were trying to get everyone seated so the plane could leave). She did not ask any passengers to move, did not tell me that I should try to ask anyone to switch seats, and we were fortunate that it didn't come down to me having to ask someone to move, as I said a single passenger must have been watching my conversation with the flight attendant and took pity on me and moved so that I could sit semi-close to my son. That first plane ride was rough for him and I was simply sharing my story with the poster so that she could make sure not to have a similar issue. It was a bad start to an otherwise lovely vacation.