Notes for Improvement:
Outline form needs to be narrow than what you have right now, the isthmus width should be only be made 1mm. You need to look at how your buccal and lingual extensions need to be narrow as well (video down below). The gingival floor needs to go down to get a good clearance.
The prep needs to follow the long axis of the crown. Please review the basic hand rests:https://members.internationaldentistcentral.com/lessons/using-the-handpiece-correctly/ to help you prevent the bur from slipping.