how to get my humidity higher

[siz]

Ditch the newspaper. It doesn't hold humidity at all. I personally use ReptiBark Forest Floor, it's like mulch/fine wood chips so it holds humidity much better. Make sure whatever you change it to doesn't have big enough pieces that your snake can eat them accidentally and get impacted.

edit: Oh and regarding your tank, smaller is better for a BP, they like to feel secure in a smaller enviroment. You could keep your big tank but make sure to have lots of hides that the snake can squeeze into, and you could maybe try adding some non-toxic live pants to raise humidity (and for your BP to climb on, lol).
hope this helps