Keep your hands steady but don't pull back on the reins.I would use spurs,a dressage whip would work.If she still ignores you then get a stronger bit and be more aggressive with her.Has she always ignored you like this?Hopefully this helped!
Put some poles on the ground where she can walk in between and practice. Than give her more and more space between the poles by moving them further apart.
Try keeping your hands wide like side reins and if that doesn't work maybe find someone to help you from the ground
Struggling with the same problem :(
Try to push her out in front of your leg before you do anything else, a crop and some spurs can help if she's acting like she doesn't hear your aids. I've found that for horses that won't go straight forward is always the answer.
I had a problem like that with my trainer's mare Katrin. I figured out how to go straight by realizing that my outside rein was floppy but I don't know maybe try to have more of a contact with the outside rein.