Sometimes you can wait a bit to repot, if the existing media is not broken down. If it were mine, and seems the media is still good, I will keep it as is and just wait for next Spring, or whenever you see actively new growing roots and leaves again. The plant will take a rest anyways after blooming time. One size bigger would be okay. That orchid has a tendency to climb up, sometimes I think it wants to escape my container
I am more cautious with Phals, since I know they are almost always too tightly packed. But with Oncidiums, I find them more forgiving.
