Where Does it All Stop!!

Hello, guys, it's me again and for today the question I could not get off my mind was WHERE DOES IT ALL STOP? Ok, we all know the things make up other things, like how cells make Tissues makes Organs make Systems make Body/Organism and so on until we get to the universe which is either expanding or not(depending on what you believe) I personally think it is expanding. But The focus of this topic is what if we go the opposite way.

Remember that scene from ant man when he shrunk and just kept on shrinking? Well ignoring the impossibility of that situation, would he have kept on shrinking or would it come to a point where he would get so small that things would be made up of themselves. So basically my question is how small is the smallest and where does it all stop.

Ok so yeah you can look up this qustion but what fun would that be? I would love for you guys to just let your imagination run wild:)