Thanks for explaining your situation in greater detail. I will see if we can help you investigate what might be causing your situation. The first thing to understand is the two possible causes for restrictions in range of motion: tension and compression.
This is your journey - I can only act as a guide to help you come to your own understanding. As a guide, I would recommend you learn the vital differences between restrictions to your range of motion caused by tension (a feeling of stretching) and when it is caused by compression (a feeling of stuckness.) Please read this chapter in YinSights on the Limits to Flexibility
. You will learn how to distinguish between these two limiting factors. Know that, if you are experiencing tension, you have further to go and over time, your yoga practice will help you extend your range of motion. However, if you have reached the point of compression, your journey is over for that joint in that direction. This does not mean that you shouldn't stress that area, it simply means don't try to go further than that because you may risk injury.
When you understand these two critical concepts, we can next start to delve into the areas of the body you are targeting. Let's keep this simple at first and just look at one area: your hips. I will invite you to read this post
about someone else who also has extremely tight hips. There is a lot here for you to digest. Please read it a few times so that you understand it clearly.
Once you have done all this homework, let us know what you think is stopping you in the seated poses like Butterfly
(which I suspect is the pose you were describing in your first point). Do you think it is tension or compression? Once you have answered that question, let's re-connect and chat some more.