This is clearly pretty light for you because you are able to pull it straight up even with less than ideal mechanics. If it were heavier the bar would likely pull you into the correct place or it would not break off of the ground. Your hips are too high/ shoulders too far in front of the bar. Rock back and get your shoulders further back/ hips down just a little bit. Once you are in the correct start position squeeze your lats to keep the bar pinned to your legs. Imagine trying to bend the bar around your shins as if it were made of rubber.