If you have already researched TST congregations and determined that there is not a congregation near you, there are a few options you can pursue for getting involved.
You can consider volunteering for a TST campaign. One of the advantage of campaigns is they are usually national or global in their scope, so it doesn’t matter where you live or whether you live close to other volunteers working on the same project.
You may be interested in starting a new congregation in your area. This can be very rewarding, but also takes a lot of time and dedication. Make sure you are ready for commitment, and not a quick fix.