When you walk you head bobs up and down a bit, maybe an inch. When you jog you head bobs up and down quite a lot. When you run your head bobs a bit like when you walk. The reason is because when you jog your body has to pause and wait for the other foot to catch up. When running and walking your body times everything out much better and you get a smoother vertical movement. Analyze some reference footage, take it of yourself if you want, and walk, jog, then run.
I also thing her arms are timed wrong. You should have her arm in the middle of its arc for 1 frame, then the other frames it should be closer to then ends. When you swing your arms you have to slow down and turn around, so therefore your arm has to spend more time at the ends.
Well, hope this helps.