Merge multiple tables

in Power Query all is Tables so you can add new column named Month and then write there for each month table: January, February etc..., I think your csv files has name like January, February etc
your imported csv are tables now and total row (sum row footer) and contain maybe word : Total You can filter it out
with headers, hard to say, I would like to see this.
- this is five lines in one cell? or five headers in five rows ?

instead of Combine you can Hit EDIT then you will have more options to manage these files (Tables)

edit: table should have one row of headers and no unnecessary things, total row you can add later to the result table (or Pivot - Grand Total)