i do triple science too and i have the exact same grades as u, A for all the first modules and A* for the second modules, but i havent done the second module for physics which i have next week, 2 days after my third module for chemistry.
the way your grade is determind is but adding up all the grades you got for each module and your ISA, your average grade is worked out and that is the grade you get.
so far i am one average 1 mark of an A* for Chemisty so i have to get a high A* next week in my exam if i want to average out my grade to make it an A*.
i dont know my average for physics and biology because my teacher hasnt told me.