As far as considering myself to be no more of a student or at some stage of completion, I learned long ago in electronics (my old day profession) that learning never ceases, that one is always a student. I hope to keep learning in piano for as long as I live.l even to be able to teach and share because it is joyful.
In this regard, you are well equipped to start passing your piano knowledge onto others. You have a very good mindset for learning, and this will only help you in teaching. There are many "professional" piano teachers I have met where the idea of continual life long learning is not even on the radar, to them learning only happens in the classroom, and once one is out of school, that person relieves themselves of their responsibility to continually update their state of knowledge. They have convinced themselves that they can't learn without a teacher or classroom setting. These people can breed a culture of dependence on the teacher, so the student feels the need to always run to the teacher for every small problem they encounter. A much heather approach would present the student with manageable hurdles, which they can successfully struggle through and work out on their own.
Teaching is a form of learning, so the teacher will also be moving forward in their own musical journey. If you can effectively teach a concept to another person, it means you have reached a point of understanding of that concept on your own part.