In the first photo it looks like your wrists are lower than the level of the bar. Usually, flat bar bikes are set up with the brake levers about 10 to 15 degrees below the horizontal plane so that when your finger are on the levers and palms on the bar your wrist is straight. This might be something your bike shop can help you with.
I would also encourage you to invest in some bar-ends, because they will let you put your hands in the more neutral "hand-shake" position at least part time while riding.
The other thing I notice is that it appears that you may be locking your elbows. I can't be sure because of the long sleeves. Try to make a conscious effort to relax your grip, keep your wrists straight and elbows slightly flexed. All much easier said than done. I often ride with one hand just touching the bar or even on my thigh to give the nerves a break.
Try different brands of gloves. For me the Specialized gloves work better than PI.
We do need another picture with you leg maximally straightened to better judge whether you need to raise/move your seat. The goal isn't to have a perfectly straight leg but with less angle than you are showing in any of the pictures on this round.