Firstly find the stance rotation that naturally brings the sights up and down the centre of the target. Or if that just isn't stable pick a stable stance and make it become natural over time.
Do you notice when your on the target and breathe in and out the rifle goes up and down. Inhale/exhale to get the rifle to the right height.
What I find helps, might not be good advice though, (assuming right handed) I pull the rifle into my shoulder with my right hand, I do not grip with the left hand.
Keep trying and keep practicing, it takes time to become comfortable with the position, there are more variables (muscles) affecting the stability of the rifle than in other positions.
And wind the scope right up to 32x, then you know when you are on centre, but don't snatch the trigger.
Matt