Heh, if I follow your system, then I would be in College already.
I know, it's indeed confusing. It just crosses everywhere depending on how good you are and what you want to do in the future. But if I follow your example, the high school in your country is middle in my country, only it can take longer/shorter depending on what you do.....
Well, of course it's still the lower school which goes till the 8th grade, then you have middle school, which starts again from grade 1. How far the grades goes depends on if you're doing VMBO, HAVO etc. Then there's high school, which starts from grade 1 again. And again, the amount of grades depends if you're doing VWO, MBO, HBO etc.
Yeah, probably way different that your country.....