Renew your passport while in the States. Due to Covid in Thailand, you may find it challenging at the American Embassy. Plus you are expected to have six months validity before you travel abroad.
Of course you have to prove she is a British citizen to get a British passport. And hope you are legally married to your Thai partner and your name is on the birth certificate.
You can get alot of good information from the Canadian Embassy in Bangkok about the best visa and what conditions you face to take your Thai wife to Canada.