Bank for mortgaging home

My GF and I are going to marry in January, and we have bought a new build house with the land for around 2.6 million. I have paid 500k deposit to get the keys and move in, and spent another million extending and decorating the house to a high standard.

The problem I have is the financing from the building company - It's 13% over 15 years meaning the price paid for the house is almost double!

So the house is worth considerably more, and I want to move the mortgage to a bank to bring down the interest rates and shorten the time period of the loan. Is there a Thai bank that will do this for us?

We are in our mid 30's, I earn around 1.5 - 1.7 million Baht per annum working remotely. I do not have a WP as I consult for companies abroad with no presence in Thailand and I do not pay taxes yet, as the digital tax law doesn't come into effect until next year. I have three to four years worth of financial statements and all of my income is sent to a Thai bank directly from the US. My GF has no job, but has friends who are happy to say she has one in a salon.