I developed a GUI app in Python 3. I want to be able to launch it by clicking on the script itself or in a custom-made launching script. I have changed permissions and it's now opening with "Python Launcher" on double-click. But everytime I run my app, I get a lot of windows:

My Python application (that's the only one I need to be on screen) 
The Python launcher preferences (I could live with this one, but
would prefer it to be hidden)
A Terminal window with the default shell (don't need this one) 
Another Terminal window showing the output of the app (like print, errors... I don't want this window)

What is the easiest way to get only the GUI on screen, without any Terminal windows?
By changing the file extension to .pyw (Python Windowed), any terminal/shell/cmd would be hidden by default (I even don't know about the preferences window).
Hope this helps!
How to run a Python 3 tkinter app without opening any Terminal windows in Mac OS X?