you may be starting with her too close, and , you allow her to make the wrong choice when you ask with your flag, and wait too long to correct it.
see, if she's out there and you ask for forward with the flag, and she take a step toward you, right there you make that choice uncomfortable, and make it uncomfortable enough that she very quickly seeks a different choice. you probably are waiting until she has taken more than the one step vefore you start trying to stop that. in fact, you can even catch that incorrect choice before she even takes a step toward you. watch her, you'll see her thinking about moving in on you, her body will rock forward toward you even before she moves her foot. right there, you use the flag in front of you, with a little flutter, and if she takes that step, get big faster. don't let her get in close before you start taking measures. do it when she is just thinking about moving in. the smaller her "push" on you (as light as a though, but not as heavy as a step) the smaller your push back needs to be. but, it always has to be just a tad bigger, so she feels that that is not the "right" choice and so she'll start again and make a new choice. wait, and somewhere she'll choose to go forward, and let her, then take all the pressure off for a bit.
do this a few times where all you want is for her to make the choice to go forward. don't worry about keeping that forward. once she is consistent on choosing forward when you ask for forward, then once she does step forward, focus the flag at her midsection and start turning with her, so she circles and walks forward.