While she sits I get down to her level, hold onto the sides of her head look her into the eyes and tell her "no pulling!".
This might be effective on a 4 year old child, but you are not teaching your puppy anything by doing this other than scaring her a little when you get in her face. You are probably being a little counter productive, especially when you have her sit (which should be rewarded by continuing the walk) and then you are holding her head telling her "no pulling" when she's not even pulling at the time. Dogs don't have the thought process to think in retrospect, she is not going to associate her pulling a minute ago with your correction while she is sitting. I would just keep doing what you are doing, even at the top of the steps, just stop when she pulls, continue walking when the leash is loose.
This usually calms her down and we resume our walk with her just pulling on the leash, which I can handle but hope to be able to eliminate. Then if she sees something, anything to distract her the whole episode begins again... and she becomes a lot less willing to sit so we can resume our walk.
Honestly, I would stop the walks until you have trained her to walk nicely. Everytime she pulls and you allow her to go forward, you are rewarding her, confirming that if she pulls, she gets to move forward. Did you check out the links that I provided for you? Both were very helpful in correcting my puller.
