Edward,
Good to hear you are having success using a peanut around your spine and add movements where needed.
Does more pressure elicit pain?
What did the person say about too much pressure damaging tissue?

One rule of thumb if it feels sketchy it is so don’t continue doing it.
From the Basic Rules for Mobilizing video from the getting started section.
Should be able to take moderate compression on a tissue load on that tissue.
If it is painful that indicate you have a tissue restriction.
If you can’t take a full breath while mobilizing you have completely fixed or solved that problem.
Can use breath quality as an indicator that maybe you are working too deep, or you haven’t solved the problem.
Should be able to take full/normal weight on a tissue, should be pain free to compression, be be able to breathe.

Does this help?
Other questions?