Chances are she doesn't know she's hurting you when she bites.
The way we've dealt with biting in our house is to immediately pull out the pack leader card, say No, in a firm calm voice and stop all activity then redirect. For example, if she tries to go on the couch, say NO in a firm voice while maintaining eye contact, stop any activity (so she knows this is not a game), then redirect her to the floor with a toy or a favorite blanket.
Some folks in EBN do something different - like yelping ouch in doggie talk and stopping all activity.
Adolescence usually means a lot more energy - so if she's wanting to play after a poop, that's probably why she's nipping your heels. Do the NO (or the yelp) if she nips with eye contact, stop all activity, then redirect with play time. Unless you don't want to play then you can just walk her back home and give her a toy to play with at home.
The main thing is to let her know biting is not acceptable but still maintain positive reinforcement.