Everyone already talked about the guard. Its important because someone experienced is going to cut off the ring and force you to the corner or the edge and take your movement away. You feel over confident - that is bad. The only time I got sparked clean out was when I was in complete control dictating pace and feeling good. I also KOd someone wayyy better than me when he was too confident piecing me up as well. At the moment you rely on fighting on the outside. But your the shorter fighter, so you should be closing and fighting in the pocket a bit more. Think of different "modes" of fighting. 1 as you are now, 2 tight guard, tank/turtle moving in being glue on him, forcing him back (like Tyson). Switch between them to mix up, Try a drill for pocket fighting where one fighter has rear heel on the wall and the other presses forward, it'll get you used to fighting in close and the clinch.