Walk with purpose more. Have more attitude when leading too.
Also, vary up what you are doing, in terms of speed, and stop dead and just stand there.
It is not normal for horse to be "gazing at you and focused on you" either. While they should pay attention, it is not like they are waiting for you to wax eloquent on the state of affairs in the UK, they don't need to be focused on you 100% most of the time, while they are hanging around waiting to see what you are going to do next.
TL has right idea with lash whip, trailing behind to give horse idea to come up. It could also be this horse has been lead this way, as many western people lead like this. And also use a voice command, come up, or a click, but something to get her to focus on you, and move up. And make sure you are not changing mind from time to time, and stay consistent.
You need to get the horse leading both ways though, if that was case.
And don't look at her, when she is lagging behind, as that will slow one, or lock one too.
Make sure your back is straight, and you appear businesslike too, as horses respond to that as sign that you are in charge.
Horses make me a better person.