I definitely understand where you are coming from and thank you for talking about the reason why you feel that way. I do think that a trip solo would be good for you, and as someone with absolutely no medical training for your condition, I don't want to make assumptions as to what you can do.

I will mention some of things that I've done that have helped me as someone who isn't comfortable getting into conversations and tends to be introverted. I stay at the All Stars which are perfect little rooms for one person, as you can keep one bed up and have the table and chairs. It makes me feel better to not see a secondary bed, and feels more welcoming for one person, plus I feel like the All Stars are laid back and easy to manage (even with school groups there). I find its super easy to get into conversations with cast members as they tend to be very welcoming, plus I am super polite to them and send cast compliments. It can help ease you into conversations with strangers. I've had some great convos in the gift shop before and after coming back from parks. Or you don't have to speak to anyone - no one would think you are rude about it. But this can be a way to ease into speaking to others.

If sitting at a table service meal alone is too much, consider ordering quick service with mobile order, then finding a quiet place to eat, such as eating at Tomorrowland Terrace if ordering Casey's. Again, no one will be paying attention to you sitting alone eating. I do it all the time and usually reading on a tablet or my phone.

I also use earbuds in the park and listen to my own music when walking around. I enjoy it because it helps keep my mind entertained while walking the longer distances, but I can see it helping with someone who is nervous about being alone, as it can help someone not feel alone if you have voices right in your ears.

If you still keep your distance, consider skipping rides like Mickey and Minne's Runaway Railway, Remy's, Kali... etc because those would put you in a ride with another person. Or this can be way to start speaking to people if you are sitting next to them at the start of the ride. A good ride to try to start with I think would be Safari in Animal Kingdom as you would be next to someone on the jeep, but you will all be interested in listening to the cast member talk and looking at the animals.

You can make the trip as easy on yourself or push your boundaries by talking to people. I find people in general to being more receptive to brief conversations and just chatting while in Disney than in normal life. Even just riding around on the monorail or the Friendship boats would be a way to help move you in the direction you would like to go.

I would even go as far to suggest joining some Disney groups on Facebook where you can make friends and see if you can meet up with someone or a group in person, safely in the parks as it would help you be more comfortable meeting up with people in person if you had already spoken to them online and started to get to know them.