im guessing this was just sparing, and you are wearing boxing gloves so it was not a real fight, that spinning back wrist punch would have easily damaged or even broke your wrist as opposite pressure is applied, thats why u dont see people punching with the back of their hands, and you was throwing punches with your bodu weight, thats a very bad mistake as you almost fell over when you missed so if that fat guy even layed a finger on u, u would have been on the ground your punches were all over the place and u had no timing, this was not the best fight ever, just u was excited u beat a fat kid and had to show everyone, and yes take it from a pro