When I started taking accordion lessons, my first teacher would have me sometimes move on to another piece before I mastered it, at least "mastering it" in my thinking. I think it was to get over a "hump" of learning....your teacher stated "stepping stones." These steps were both for me, and the teacher, in order to see how I progressed. Sometimes with a little harder piece, e.g. one that had RH trills in it, I would be on that a little longer. Eventually the fingers synced and worked it out. Lots of different things kind of controlled how long a piece stayed on my weekly music stand.
Would your teacher be willing, if you asked, to continue on a piece you really wanted to master? Seems like that makes sense, especially from your learning need to pull it more together.
I remember one other thing that actually was a little sad for me to see. But I realize now it was practical, and did need to happen. One of the new students just starting like me, had a "conference" with his teacher and parents and music center owner. The result was that the teacher's recommendation was that the student was not grasping how to play very well at all. The teacher suggested he "quit" the accordion. Tough stuff. I think in a way some parents may have be grateful rather than continuing to pay for lessons.
At the end of the day, you can always find a different teacher with whom you can more smoothly work with. We newbies, along with our parents, were told that also when we started out. A teacher change sometimes made a world of difference.