Is it possible to infer immediate and overall projection from calculator measurements? [26f/ff]

this is a general question but I am not able to post without including my size.

title! I'm still on the hunt for a well fitting bra and suspect projection issues with some of the bras I've tried, though I think I need a little bit of help understanding the difference between overall and immediate projection.

My understanding is that overall projection refers to the volume of breast tissue overall, and immediate projection refers to the volume where the breast attaches to the chest wall. If I'm understanding correctly, these are not dependent on each other.

If this is the case, then if someone's leaning bust measurement is greater than their standing bust measurement, would this imply immediate projection? Similarly, a standing bust measurement greater than or equal to the leaning bust measurement would imply having overall projection with little immediate projection?

Does this sound right, or am I totally misunderstanding this?