yes, you are missing the question in your post.
I hold a masters degree (Total - 18 Yrs of education) and applied to AINP with following entries in imm0008 generic form - education section: primary (8yrs), high school (4yrs) ,college/univ (6yrs) and post secondary (0 yrs).
this looks ok, since 8+4+6 = 18, and you seem to have accounted for your bachelors + masters correctly.
as far as first 12 years of education, there is no set standard - if you studied 8 + 4, that's what you did! some write 7 + 5 if that's how it's broken down in their country.
everything looks fine to me, but then, i'm not an immigration officer either

these many years of education, and they never taught you to spell 'education' correctly - tsk, tsk (sorry, couldn't resist)