Nothing like dealing with cancer in the past tense! Can't answer all your questions but starting with the last.
You may well be cancer free, just that no medical person has enough evidence to say so, so they won't. Treatment was designed to kill off any stray cells that escaped the lumpectomy but it's not a perfect science. There is unfortunately no guarantee that you will stay cancer free after 5 years ( I have just passed mine) but your chance of a recurrence from the original cancer shrinks very significantly. Scan anxiety is a thing - while threads on this website are devoted to it.