I understand what you want to know, I wondered exactly the same thing for many years, but now I don't think I can answer that in any way that tells you what you want to know.
The nearest I can get is that they don't feel anything, they are simply there, and seem
right
If I touch them, feel them with my hands, they feel like the small real breasts that they are.
Physically, if I run or even walk fast, without a bra, they jerk up and down and feel uncomfortable, but not quite painful. If I knock them against something it is anything from painful to absolute agony, depending on the severity of impact, and they constantly surprise me when I walk to close to things like door frames or try to carry large things by hugging them to my chest as I have done all my life!
Have I changed my mind? Absolutely NOT!