hey jenny, new to the forums, (followed a few friends over here) and saw your post about the pullup progress.
My wife used a chair to get her first full on pullups, we have the same setup with a door gym type bar.
just throw the chair (just like a normal dining room table chair) under you, a little forward and use that as support with one leg to do pullups, like a weight assist.
she would stand on the chair, lift herself up to the top of the pullup and do timed holds, then timed negative pullups, and you always have the chair under you to step down on.
hope that helps, good luck with your progress!