LMW if the halti is giving temporary help with pulling but you would like to gradually change to a flat collar you could try walking her on both the flat collar and the halti.
You can have two leads. Just hold the halti one loose and walk her on the flat collar lead, even using some of the ideas above to help her understand how to walk nicely on her flat collar. If she starts to pull or you don't feel you have control you can use the halti lead for a short time. If she settles and stops pulling again, loosen the halti lead and walk her on her flat collar again.
I do this with my girl who still pulls sometimes. I have an Infin8 head collar from Blackdog for her. The beauty of this one is that the strap that goes around their face can be unclipped if they are walking well, and the base part of the collar works like a normal martingale collar. It's a great way to wean them off the headcollar.
I do find with her that her pulling is normally only excitement based - she's not being naughty. If she's in a pulling mood she normally eases off once she settles into her walk.