It sounds like you've had some not-so-great doctors before. I can understand how you'd want to avoid that, then, that's fair enough!

One of the defining factors in SPD is a lack of desire for human connections. So, if that's something you desire but you avoid because of anxiety... my guess would be that it's not likely to be SPD. That is a part of several other disorders, however. What you'd have specifically can depend on many different factors.

You mentioned you had reservations about therapy. Therapy isn't (or shouldn't be) just you talking to someone for a while like paying for a sounding board. You may be interested in checking out DBT. It's a highly effective type of therapy for a lot of people that has a lot of scientific studies to back it up. You may be interested in this article 9 Myths and Facts About Therapy | Psych Central
It also doesn't always have to be that expensive if money is an issue. There are usually options for people who can't afford as much.
Either way, I'd encourage you to at least check out the possibility of it. It's really helped a lot of people.

There's always self-help books you can go to and coming on these forums the way you are is really great as well.