5) . . . I find I can just follow one method. I can maybe flick focus between 2 things but can't do all.
That is a logical conclusion, supported by your experience, and it is a clear statement. Well done.

6) Next the sensations in my chest and/or abdomen area. From what I understand I am supposed to simply watch my sensations and since they are impermanent they should fade away. But these sensations don't fade away. They stay as long as I am aware of them.
Again, you are clear and honest about what you experience.

But . . . Then you do tell about their impermanence:
You tell, that the pressure/pain in this area intensifies with more thoughts. Also, you have found that you feel these sensations only when you focus on them. And you tell that the thoughts turn into a burning sensation.
So they are not hewn in stone, they change.
So, what happens is not really that they 'fade away'. They do not vanish into thin air - that is not what you experienced. Also, it is not true that they simply stay as they are.
It is common to find that in meditation: "Hey, my thoughts / feelings do not do what I want them to do".
Also you tell of a later step in the training of the mind:
After finding that you cannot simply will the thoughts and feelings away, you find that you can have a subtle influence:
The more I am mindful of these sensations, the more they intensify. So much so that if I lose focus again and then come back after a few minutes, I still feel the burning from the earlier intensified feeling, although less now. But if I stay at it, it intensifies.
I hope that I am not confusing you. I see three steps:
A. You find in you practice that it does not work the way you thought it would work.
B. You do find out about impermanence and how thoughts and feelings go in a kind of process of their own
C. You find that after all, you can take some influence, through focus.
Well then, let us now skip to this:
In fact, any pressure/pain in this area intensifies with more thoughts especially painful, angry, guilty, desire thoughts and finally turns into a burning sensation which may or may not spread to my entire chest,abdomen, throat and shoulders.
To me this sounds as a cleansing. Do I guess well, that once you can spread the burning sensation, you can let go of the angry, guilty thoughts? I suppose that a process is going on that so to speak burns away the angry, guilty and desire thoughts. Could that be so?
The more I am mindful of these sensations, the more they intensify. So much so that if I lose focus again and then come back after a few minutes, I still feel the burning from the earlier intensified feeling, although less now.
Also this indicates to me, that a process is going on that was started up by the fact that you meditated for 10 months. A process that goes on also when you do not focus on it - and then it goes on in a milder way.
What should I be doing? . . . Has anyone had this experience?
When I had this during a retreat, my teacher told me to trust the process, and also not to focus on it or on thoughts that would intensify the process.
And that is where this advice of Matthew comes in again:
relax, trust, calm down.
Oh, I forgot: Welcome to the forum.
(Sometimes I forget how simple life is.

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