I used to work in a gear store and I spent a decent amount of time fitting people for packs.
In your photos it looks like you could actually go with the medium or large setting. If you can go somewhere in between I think it will fit best for you. I can tell this because a shoulder strap should wrap around the tops of your shoulders and then attach to the pack. The shoulder straps should never be mounted below your armpits.
The biggest problem is you are taking in the load lifters TOO MUCH. People automatically want to tighten every strap as much as it can go but with backpacks it requires a delicate touch. The only straps you should crank down are the lumbar strap!
For comfort, your shoulder straps should be simply resting firm against your body and shoulders but never tugging on your shoulders. When you walk you should be able to feel a very small amount of movement of the straps against your shoulders from the pivoting of the pack on your waist. If you cannot, the load isn't transferring properly to your hips and is too much on your shoulders — the exception being packs with pivoting hipbelts or shoulder straps. You should adjust your shoulder straps with the load lifters completely slack.
Your load lifters should be taut but not cranked down. From slack, keep pulling in the load lifters until you can feel the shoulder straps being tugged on. Then pull in about a quarter to half an inch more. Load lifters are something an experienced backpacker will find themselves adjusting throughout the day to keep the shoulders comfortable and the weight properly balanced. Learn to find them while walking and play with them as you walk to see how different tensions feel. You'll get the hang of it. You won't be sore at the end of a long day.
Finally, the sternum strap should also be taut but not cranked down. One of the greatest causes of discomfort for inexperienced backpackers come from a sternum strap that is too tight. The sternum strap is simply to keep your shoulder straps from sliding off your shoulders. Many people benefit from having the shoulder straps just a little closer together than they sit without the sternum strap, but it should never be tight. Resist that urge.
Once you have everything dialed in it should be pretty comfortable. At the midpoint of a pack's weight capacity (typically 25-30 lbs for an internal frame) you should never really feel weight or tugging on your shoulders in a neutral standing position. Shoulder straps on a frame pack are more to control the pack's balance and not so much to carry weight. Most of the weight should be transferred into your hips and iliac crest. When you start to reach the top end of a pack's weight capacity you will feel some weight on your shoulders.
Hope this helps.