It will depend mostly on the individual horse. For example, my horse is very spirited and won't be as "obvious" with his signals. His ear on me is easy to tell, but he will rarely lick his lips, and has never dropped his head. However, he still joins up wonderfully.
If she kept getting more upset and more frantic you may not want to push her so hard. Monty Roberts wouldn't push them very hard for long and you can have them trot and still get a join up. My horse is a TWH and can't canter for the life of him so I usually trot (well, pace) him most of the time.
So keep it up. Some horses take longer than others. I use a similar approach for getting hard to catch horses to be caught. However, in my situation I had to do it as a herd of 3. The BLM mustang mare figured it out incredibly faster than the other two geldings (one of which was the one I was actually trying to work with).