multiple "if" functions depending on previous functions

Hi all, I'm struggling to get this formulae to work right! I'm a teacher and want to develop a grid to track marks for assessments and work out points.

If a candidate gets all the Ps ( 9 in total for unit 2) They get 12 points, if they get the 7 Ms they get another 6 points making 18, if they get all 5 Ds they get another 6 points to make 24. I have that bit sorted, the tricky part is if an M is missing, they are limited to 12 points (even if they have all the other Ms and Ds) and if any P is missing, they get 0.

Any help would be much appreciated!! See attached spreadsheet.

I have used the countif function to count the Ps, Ms and Ds in the cells as a helper column to the right.