trying to create a dynamic range based on column A cell value...index match?

I have a worksheet that has 2 columns of information (simplified version).

Column A has a non-sorted, nonlinear, list of part numbers, descriptions and some empty cells.
It is divided into variable row sections by “header” characters. These characters are [1], [2], [3], etc. UP TO [20] (with the brackets)

Column B has the associated quantities of each part.

I would like a macro that will set up columns C,D,E,F,G,H,I,J,K,L so that I can move the part quantities under rows below [1] and above [2] to column C,part quantities under rows below [2] and above [3] to column D, and so on.

When complete, all quantities will be in the same row they originated in, but would shift to the column associated with the “header” character. ( Section [1] quantities in column C., Section [2] quantities in column D.,etc.)

I've tried to use MATCH to identify the row each "header" is in to create a dynamic range, but cant seam to use the result as part of a formula...
Im running out of ideas..., could really use some help on this.

Just for clarity, the source & result should look like this:
(thanks in advance)

sort.jpg