Kept mine inside for years because I thought monsteras stayed small in pots. Total myth. Put mine on the porch last spring and it went nuts, same as yours. Learned that heat plus rain plus a pot it can't escape equals a jungle. Chopping works but it comes back thicker, so you gotta stay on it. Letting it win is a real option if you don't mind the balcony being gone. Mine ate a chair and I just gave up and bought a smaller one.