Talk to Siam Legal. They have their offices in America and cater for Americans too. Never engaged them (I met, personally the owner,an Amarican, in Bangkok) but those who did, expensive but efficient.
No FaceBook characters would take you where you want to be, just like this, for free.
I made that same mistake, picking wrong visa type and someone here (possibly you, Brandon) directed me to chose visa type that says something with "not intenting to stay longer than 90 days", something like that.
Check in at the origin ask for the return ticket, if they do. It is their responsibility to ban you from embarking the flight or transport you back if any problems, not at the destination.
I will do it myself second time around. May even let my current "Retirement Visa" expire and do it anew. First time, there were so many things (to get a yellow book for my address, the condo I own) may take a month. Without it, and Immigration certification of residence, could not open a bank account even while on a 90 days "O" visa.
For the next turn, July 2026, I will have it all ready, even 3 months from now.