At 4 months you have teething and they are cranky and chewing on everything.
It sounds like she is getting a good amount of physical exercise but you would probably see more of a change if you started adding more mental exercise for her. Do you use things like Kongs or Busy Buddies? A Buster Cube is also good. Something where she has to do some problem solving.
It is too bad you can't get into an obedience class, have you looked around to see if there are any that offer drop in type classes. Around here it is becoming much more popular to offer classes where a person can pay on a week by week basis. Many of these classes have a rotation of topics that they go through so you can drop in for the loose leash class or the sit class, etc.
Here is a nice resource for starting some training on your own. This will help give Zoe some mental stimulation which should help use up that excess puppy energy. http://www.dragonflyllama.com/%20DOGS/Levels/ByLevel/1Level.html