ATM from foreign account is bringing in money, taking cash with you is bringing in money. How well everything can be checked is another story, but be aware that you are supposed to live from something, so you should tell you bring in some money when you are tax resident and have no Thai job.
Anonieme deelnemer Thailand not even sees it as work, because on DTV there still is the remark "work prohibited". And when it is not considered as working in Thailand, the income cannot be local sourced, so until you stay 180 days or more, and bring the money in, you might have to pay tax for it.
That will work only till IO thinks you are not a tourist. And when MFA thinks non-o is the correct visa in this case, IO also might come to that conclusion, but we don't know the situation.
But the administrative problem is het was not the whole time being present in the country with her, causing different end dates for the current stay. I do not judge about this, but it is good to know that in case dependants not always stay the same time in the country, this can be logical consequences. When you want to prevent this you should arrange own visa, go our of the country together, or accept you might not have possibility to extend, but only to bounce. The DTV is not meant to stay the whole time in Thailand, there is a reason the total stay has a maximum of 360 days. So therefore you cannot expect immigration to make rules comfortable for people who try to live in Thailand.