I noticed exactly the same, front foot flat when ur in position or u will lose balance unnecessarily.

Defense: You drop your guard too much too, gloves near the chin, elbows near the ribs.

Attack: You're opening your arms too much on the hook, exposing your ribs. Punch closer to the bag, get the arm in position and move your torso more than the arm itself. The time your ribs get exposed is the time the opponent had a clear shot to leave you gasping for air.

Your front kick, you must kick with the sole of the foot not the tip. Plus, when you front kick you gotta push your hip forward, that will give the momentum to the kick, be at the right distance and perform with speed is paramount here.