In the pic of you in the pink shirt, that is the best as far as vertical alignment.
Yes, you are tilted forward but only slightly.
In the other pics , you are definitely sitting toward the back of the saddle, so that your pelvis is tilted down and forward.
You have an arch in your lower back.
It looks like you are swaybacked.
You can ride dressage in a jumping saddle , the only cavaet being that a jumping saddle can also put you in a chair seat.
I think the main thing for you is to do some short exercises where you can focus on your vertical alignment.
Shoulders over hips, heel under hip. Eyes up , chest open.
Dressage is a great discipline, but it lends itself to the mind and the body lying to each other.
For example: I was schooling one morning and someone asked if they take a photo of me for a school project. I said sure.
Well, let me tell you , it was eye opening to say the least
I thought I was in the correct position, back flat and straight .
I couldn’t have been more wrong.
I was tilted forward but my shoulders were angled back and I my fat a$$ pooched out behind me. My back was arched out, I am very surprised it didn’t hurt .
That was a very cringey moment believe me.
Trust me when I say that your position isn’t that bad.