Per category changing line items (vertically) broken down horizontally per category

Hi,
I hope somebody can help me out. I attached a file containing two sheets. The first sheet is called Input on this sheet there are several categories of which I displayed the first three on. My ultimate goal is to get the Input per category broken down horizontally over the line-items on the Output sheet. Every category contains several line items to which costs are attached (f.e. in category 10, line item 4000, the costs are 33,000$ and so on).

The problem is that every month the costs are changing per line-item, but also the number of line items per category will change due to the fact that the line-items are only displayed if there are in a specific month costs booked to the line-item. In other words sometimes line-items are added due to costs booked at the line-item, but if in one month there are no costs booked at the line-item it disappears from the overview. A formula containing: '=if(category=10,vlookup(... is to static due to the changing line-items.

I hope I made myself clear and hopefully somebody know a solution

Thanks in advance

Fredstyler