One thing I don't understand. How come the immigration accept an insurance with a high deductible amount? Isn't the insurance supposed to pay health expenses from 1 to 400,000 baht?
You should have asked for a yellow book with your name when your wife got the blue one, so you won't need a power of attorney. It's not too late to request one.
When did you got your extension? I don't believe you got it 90 days ago. That maybe the reason. You have to count the 90 days from the last time you got your extension of stay.