One flow per button is needed if you use an “else” in the then part of your flows.You get that by dragging a card down until it appears. If the and part fails, the else is executed.
I do not own shelly blinds so I do not know if you can see that they are moving. What ou can do about it if it does not, is use a timer app like Chronograph - Adds precise timer, stopwatch and transition functionality to Homey or similar.
If you start a timer when you start the action, you can check if that timer is still running to detect the second push.
Having many flows is inherent to the design of flow triggers. It is how Athom keeps Homey running efficient. My advice is not to fight it, but organise your flows in folders and use naming conventions.