I think your to hard to yourself, for me the head shapes are looking fine.
I think the ones matching the photos are a bit off with the direction they are looking at.
The one on the left side, second from bottom. I think your drawing is rotated a bit to much, her head is oriented more straight to the viewer. It seem like you lined up the head more with the direction her eyes are looking.
It all takes practise and looking back at the older things your created from time to time.
As i´m not too happy with the progress either, i´m hesitating a bit to gave critic.
Also for your gesture drawings, at the moment my goal with them is, that the viewer can see in which pose the character is and that without having to guess, just a quick look and he see´s it right. That the poses look more fluid and elegant is something i try to archive if the 30s i´m doing most, feel like a eternity to quickly sketch the pose.
With that said, i think you managed to show in which gesture your models are quite well. Beside a few exceptions i look at the gesture and can see right away in which pose the model is.
Hope it helped a bit.
And keep up the practise