I've never found a mythstone

I’m relatively new to the game. I’m a level 26 rogue playing difficulty “legend” but got to act three on easy before I switched. I’m on level fourteen now and have never found a mythstone playing easy or legend. I’ve tried using a mythstone find boost but that hasn’t helped either. I only have three regular bags. Do I need a mythstone stash in order to find mythstones? Am I doing something wrong? Do I need to get further in the game, or do I just have the world’s worst luck?

as far as i know… if im not wrong… mythstone will start drop after map lvl 21 and up… if it not drop for you after that map… that mean something is very wrong… even worst i can do… i think 2 run should give you one mythstone… but maybe just RNG god just hate you… just try again on higher lvl…

Just keep playing and going to higher floors.