Girl I knew once you relaxed it would click for you! :)
Now each ride once she gets really good at allowing contact and you are good with giving the rein once she gives, you can begin to put more leg on so she really steps under herself and begins to use more of her hind end instead of being heavy in front.
You can start doing lots and lots of figures and transitions (a few strides of each gait before you transition up or down) and she'll start to use her back more so.
But don't rush the process.. so bit by bit. Gauge what she's ready for, and what you are ready for :)
"Strength is the ability to use a muscle without tension"