You can only travel internationally with a passport. Without a passport, you cannot enter Thailand and there is no point to fill out a Thai visa application without a valid passport.

@Brandon ***********

is correct. unfortunately the Chicago Consulate or the U.S. based consulates does not respond to any calls since Covid. The online visa you applied for does get Chicago’s endorsement and final visa is issued in Thailand online. Website recommends at least 15 days to submit online applications and most people have gotten a reply in 5 business days.

@John *****

TM6 are no longer used. In place is the boarding pass aka arrival card is what immigration is asking for. This is the card of your aircraft seat assignment which shows your name, flight information, seat assignment, etc. At immigration, they will ask for your passport and boarding pass. Policy changed sometime after Covid for aircraft arrivals. Unknown to all travelers, this is an important document as the cabin crew doesn’t tell you this.

Your boarding pass (arrival card) to get you on the aircraft

That arrival card is your boarding pass

With a Non-O VISA for family/marriage, you can apply for a 1 year VISA which gets you multiple entries at 90 days each entry. Just fly out to a neighboring country for a few days or more, then return to Thailand and you get another 90 days again. That should fulfill your 6 months stay in Thailand. Done it many times. Instructions are on the Thailand website.

These are instructions to apply for a VISA for medical purposes -