h m m . . . . I'm trying to think how to answer this. you are worried about being told things you are doing wrong, and want ideas of how to improve them . . . . hm m .
well, first of all, you're doing ok and you'll get there, and if things were easier before on that other horse, well . . . that was then, this is now.
this mare looks like she needs some help getting herself together , too, so thing might feel a bit rougher now. but, it's goinmg to work out.
a couple of small observations from those still photos;
always work toward keeping your thumbs on top. remind yourself ten zillion times.
and as much as you can, don't let yourself get into the place of pulling her back . there's a feeling in the photos that you are a bit heavy on the rein, and she's not responding to that, so there might be a bit of a tug-o-war setting up.
bending is your friend. both bending the horse's body, bending your elbows, and using one rein a bit more than other. think always of bending.
vague advice, I know. . . . that's me.