Best way to fix excess stain on hard wood floor? Or just poly it?
Your picture reveals, to my eyes, an unfortunate situation. The areas where the sun is illuminating the finish reveals that you did not sand enough, the original finish remains and that is the cause of the uneven absorption of the stain. If you really want it to look right you will need to start over, this time spending more time with the sandpaper, particularly the initial coarse paper. For even staining you need to remove all of the existing surface treatment. Sorry... it might help if you rent a drum or vibrating floor sander from a reputable tool rental shop.