She looks a bit rushed in the canter - perhaps encourage a shoulder fore, sit deep and back a bit and really support her with your outside rein.
I know you said not to critique you, but I couldn't get my tought across otherwise...I'm sorry! Your trot work looks beautiful; I love how she is really working through her back - makes for a really nice package
It looks like you are doing awesome with her! She extends beautifully, but I think she could be working her hind end even more. She has a nice head set, but you could get her even more rounded to tuck her butt right under her body and get that head framed even more. Really the only off photo was the cantering one, but others already mentioned that. I think you guys look great!
She looks like she's not quite tracking up enough.. push her forwards a tad more, and remember to every now and then let her stretch..do some long and low work and ask her to stretch down, she looks a little tight through the back.
She is looking very good though :)
I keep looking at these pictures, and I just don't think she's ready to "engage the hind end more". JDI, please don't take offense - she looks wonderful.
Speed and "pushing them into a frame" just isn't how dressage works. I fully agree with what JDI is doing in bringing her along the way she is...building muscle as she goes.
My eye says she actually IS using her hind end quite well; especially for only having been in JDI's care for 4 months. :) The really powerful work will come when she begins to collect her; the head comes up and the rump goes under :)