Google-sheets – Find value of last non blank cell in a row (while skipping specific columns)

So basically I have a list of data in a row. They are totaled weekly statistics numbers and at the end of every month, there is a "total" column. The column where the 8 is at is where this formula will go and the column with the 5 and 0 in it is where my data starts. The grey columns are the "total" columns.

I am trying to use this code =INDEX(J15:BT15,1,COUNT(J15:BT15)) to get the value of the last non-blank row. It doesn't work because the "total" column automatically populates as a sum of the weeks in that month for a "Month to date" kind of total. How would I go about skipping these "total" columns with the index formula, and if it isn't possible, how can I achieve this in a different way without relocating my data with formulas? Is there a way to do this with =query() by skipping columns with the header "total"? Very amateur at this so thank you in advance!