Unfortunately, your disability doesn't technically qualify for preboarding per Southwest's policy. Southwest allows preboarding only for customers who 1) need a specific seat on the plane, or 2) need assistance boarding the plane.
If you find that having a specific seat helps with your anxiety, that would be a way for you to preboard.
For reference, here's the full Southwest policy:
Preboarding is available for Customers who have a specific seating need to accommodate their disability and/or need assistance in boarding the aircraft or stowing an assistive device. If a Customer with a disability simply needs a little extra time to board, we will permit the Customer to board before Family Boarding, between the “A” and “B” groups. Those Customers who need extra time to board will receive a new boarding pass with an extra time designation. The designation serves as notification to our Operations (boarding) Agent that the Customer should be permitted to board before Family Boarding.
We will allow one travel companion to act as an “attendant” and preboard with a Customer with a disability. In most cases, the Customer requires assistance from only one other person, and any additional family members or friends are asked to board with their assigned group.
Customers should request preboarding from our Customer Service Agent at the ticket counter or departure gate. Our Agents are trained to ask factfinding questions to determine if the Customer meets the qualifications described above. Those Customers who qualify for preboarding will receive a new boarding pass with a preboarding designation. The designation serves as notification to our Operations (Boarding) Agent that the Customer should be permitted to preboard.
It's important to keep in mind that Customers who preboard may not occupy an exit seat.
Note: Customers who are preboarding because of a need for a specific seat onboard the aircraft should speak with the Operations (Boarding) Agent prior to the start of preboarding to alert the Agent to the seating need.
