My thought is that your seat looks a lot higher than I would want Your leg is going near straight at max extension. I like to keep a lot of knee bend. I rode seat heights like yours before racing. The vets in my club immediately had me lower it and it kept going down over the next couple of years. I now have a very simple test that dials in that seat height exactly. I sit on the bike next to a hallway wall barefoot, pedal down and heel on the spindle of the upside down pedal. There is exactly one height where I can either bent my knee or lock it straight without rocking my hips. (Others like seats a little higher than I do and do the same test with low heeled house slippers or cycling shoes. Once you have "the height' keep those shoes! Makes setting up new bikes for set height brain dead easy.)

The lower seat allows me to rotate my hips forward without needing to rock side to side over the saddle, therefore allowing real weight on my soft parts. (Yes, men and women are different, but if you look at the women pros, they do exactly the same thing on almost identical saddles.) Being able to comfortably rotate your hips forward means straightening out your lower back. Right away, this should give you some relief.

I also find relief when I set up bikes for more reach. Sounds totally backwards but hear me out. More reach means I can be pulling slightly on the bars, stretching my back, pulling those vertebra apart, not compressing them. It also feels like I get better blood flow and more oxygen throughout my torso muscles so everything feels better, especially on long climbs and hard efforts. So after lowering your seat, you may find you can remove a spacer of two from below your stem and maybe even go a touch longer with a new one.