Discus is pure tech, I am a skinny and weak bastard and can throw the 1kg over 50m without much practice. Starting the turn with your left side is key, if you focus too much on the arm holding the discus you will then have lots of balance issues.
Start leading with your left foot and arm and everything should be suddenly working propery. The discus arm and the non pivoting leg should follow, remeber that separation between limbs is what catapults the discus. Add a motion like the shown by Schult in this video and you’ll be throwing far given your span even if you lack strength: