A few extra holes in the plates are not unsafe, so no -- you didn't harm your house.
Guessing here, but your plate+subfloor+joist height+top plate of first floor is more than 12". Get an 18" installer bit (with a hole near the tip) and use it to fish the wire. Try to make sure you end up centered in the plate below.
Edit to say that you need to cut a bit more drywall back to understand that header and how to get through it. Maybe you'll get lucky and it won't go much further to the left. Maybe you'll be less lucky and have to drill through it. Any way you slice it, you need more drywall gone, and a large patch is about the same as a small patch.
