There is no ETA, that was never implemented by the Thai government. What they did instead was implement something called the TDAC (Thailand Digital Arrival Card)
I would wager you're not on any Visa at all :O , and instead if you look at your stamp it would probably say "extension of stay permitted until" and have a date. That's not a Visa that's exactly what it says it's an extension, and you have a valid reentry permit.
Be that as it may, you are indeed required to file a TDAC before you come into the country.
You can do it from 3 days before you travel right down until you're standing in the arrival hall (they have kiosks there).
While I am loathe to believe AI when it comes to almost anything to do with entry/visa/extension information to thailand (because of the plethora of bad info out there that's been repeated so many time AI thinks it actually true 😮 )
This does appear to be the changes they implemented
You have a valid one year, multi-entry Non-OA visa (that you got from the thai consulate in your country before you came here) and that visa is still valid 🙂
AND
You want to bounce out/back before the Non-OA visa itself expires and get a new entry stamp for a year <- is that correct?
Remember you also need a new year of the mandatory 100K USD health insurance too (they will want to see it at the border when you stamp back in)
You're not talking about Immigrations either, you're talking about the border crossing people at passport control and those don't close for weekends or holidays, they're open every day of the year at the Nong Khai border .
Stamp you're currently on and the previous extensions that are in that passport and if you got a new passport it will already have the transferred stamps in it
it seems that KL has their processing time back down to just a few working days (but it might just be because you're a Malay they have faster processing because usually that is a SLOW consulate)
Remember to print your PDF eVisa because that is your actual visa
With over 80 offices in the country, your best bet is to head on over to the Saraburi Immigration office well before you're going to apply for the year extension and ask them what they want for proof of address.
Usually it's more than just the TM30 (notification of foreigner in residence)
If I was to guess, I'd say you're most likely going to need your g/f's lease, thai i/d, probably the landlord i/d, maybe the house book of that property in addition to the TM30 receipt you have showing you're registered as staying there