Begginer here: Can't get my draw shots, and stun shots to work

So basicly, almost every time I play with backspin, I encounter 2 problems: 1: the cue ball starts rolling back but rolls uncontrollably, even in practice shots, and 2: The cue ball, instead of going back, it gains spin but follows through. And when I play stun shots, the cb actually moves a bit forward after contacting the ball. To be honest, I don't really pay attention to my grip, but I'm not sure if I hit the cue ball straight. It looks straight to me and my cue and aiming line are straight. I attached a video here. Thanks in advance for you help!