What type of visa am I currently holding after extending my entry due to having a Thai parent?

you're not on ANY visa 😮 you came in visa exempt (as a thai using another country passport) you got a year extension based on having a thai parent)

Sadly opening a bank account isn't part of what this group does.

post on the thai citizenship group or a group related to where you live in thailand and you will get recommendations on where you can open an account.

Being a thai national (which you are whether it's been recognized or not) means you should be able to get an account open anywhere, by showing your birth certificate and the thai i/d of your thai parent

The stamp ON your extension says มารดาไทย <- thai mother, so take her OR one of your relatives with you to go try to open an account.