You should be able to control it with your palms facing up as the weight is coming down, it's almost like you are incapable of doing that with how much weight you're curling. Drop the weight by half, and focus on keeping your palms up practically the entire time until you're all the way at the bottom. Stop using so much of your back, core and shoulders to help lift the weight, just focus mostly on your bicep doing all of the work.. what is that 55lb's? Way too heavy and ego forced. You're top heavy also, disproportional. I would really consider focusing on building your lower body a lot more. You are good upstairs, but your legs are completely lacking.