I've worn a Deuter ACT Lite 65+10 all summer. I'm not certain if the load-bearing systems are the same, but I found that I can get the best & closest fit by loosening all the straps, then tightening the hip belt first, then the shoulder straps to snug the load against my back; then the load lifter straps to adjust the load vertically up or down on my back. (The position of the load weight will vary depending upon how many water bladders and which tent I'm carrying). Sternum strap last, to set the shoulder straps into the most comfortable position.

You may need to move the shoulder straps down a notch or two so they are not riding up so high and gapping to your shoulders, but if you've been carrying the pack with no discomfort it sounds like you are carrying most or all of the weight on your hips which is good.

This is a little ritual every time the pack comes of and goes back on. I will admit most of my hiking and backpacking is on roadways or very hard-packed trails and the closer and tighter I can carry my pack, the less impact there is on my legs and knees. Which is also the reason I bought the Deuter ACT Lite to begin with.