If putting your cells in a "x"p configuration, then make sure that all the "x"s connected cells are at the same mah!
It does not matter if the cells in the "x"p configuration are (for example!) 800mah and 1200mah, but they will give 2000mah.
Make sure the rest of the "x"p "packs" are also in the 2000mah range.
I presume that you are using new cells?
If a cell get older it will give not so much as when they were new.
If your cells were new and give 2000mah and now they give (remaining mah) a 1000mah, it is time to buy new.(50%soh)
in certain cases you can do without a bms, but you will need a balancing bord in case of a 2s or more.
This has to do with the certain charge and discharge speed of the cell itself.
In any case you would need a charging board that match with the chemistry of the cell
You already have a balancer-charger. why change?
I can set a 100 stages for you, but i would like then to have some more info:
operating V
number of P arralel and the number of S eries.
For now i would say a cheap charging and or balancing board will do what you need, match your cells and match your balancing or charging board accordingly to your "x"s
with best regards Igor