Good work :)
She is very much on the forehand in these photos, and reefing the reins through your hands.
She looks to have a lovely strong, soft back and good bend through her hind legs, there shouldn't be any reason for her to be travelling on the forehand.
You are gripping with your knees, straightening your arms and tipping all of your weight onto her shoulders. Try instead, to think about sitting back, releasing your knee and upper leg, bringing your elbow back to your waist and allowing it to act as a hinge - always with bend in it - in order to 'lift' your horse's forehand. Something as simple as looking down can put a horse on the forehand, so it is really important that you think of riding the forehand up, and pushing the hind quarters down.
I wouldn't be working her so low - I know everyone loves "long and low", but it is a pointless exercise if the horse is on the forehand - it actually takes a lot of strength and balance from the horse to remain in self carriage through long and low work.
You want to think about lengthening her neck out from the withers, with the poll as the highest point. So she can stay in a long, stretching frame, but with the head and neck more elevated she will find it easier to engage her hind legs and lift her wither.
Try some simple leg yield work with her, and lots and changes of rein, transitions and circle sizes. She's a a lovely hindquarter on her - use it! :)