I believe Blackhole in MilkyWay expanded to 3 million mile .diameter. What was its diameter 25,800.years ago?

I would also like to know if it's believed the Mily Way had a Blackhole 25,800. years ago. Did this phenomenon move into our Galaxy or was it always here. If the Universe is expanding then the Galaxy is also so it stands to reason the Black hole has also expanded. When our sun ped through the Galactic Equator 25,800. years ago, I believe the Blackhole either was not yet there or was much smaller than the sun's diameter.