hellomy cat Squee likes to bite gently too and I know how it is
you got it from a Humane society so its likely the cat has been abused before you got to it.
Thats ok you just have to let the animal know that its NOT ok to bite. Blowing on their face is one thing to deter them or staying away from sensative areas that cats see as attack zones like the throat and stomache. I also make a "SSSSSS" sound which makes my cats know that its not ok. Its very effective.
thats only a recomendation and its really helped me when dealing with feral cats.
good luck.