Formula returning the value of the cell below a reference cell

In the first tab of a worksheet, I have the weeks and the corresponding month in columns:

Week # Month # days
1 Jan 5
2 Jan 5
3 Jan 5
4 Jan 5
5(1) Jan 2
5(2) Feb 3
6 Feb 5
7 Feb 5
8 Feb 5
9(1) Feb 3
9(2) Mar 2
10 Mar 5
11 Mar 5
12 Mar 5
13 Mar 5
14 Apr 5
15 Apr 5
16 Apr 5
17 Apr 5
18(1) Apr 1
18(2) May 4
19 May 5
20 May 5
21 May 5

In a second tab, I have a profitability analysis by week:

Week 6 7 8 9 10 11 12

Revenue - - - - - - -
Costs - - - - - - -
Margin - - - - - - -

Projects can start at any point, so the first week (6 in the example above) is not always the same.
I want the model to automatically populate the cells to the right of the starting week based on the calendar above. So the last week of Feb should be 9(1) and the first week of march 9(2). What formula can I use?

Sample file attached.

Then I would need to see 7, 8, 9(1), 9(2), 10, 11
(sequence as per the calendar)

Thanks!