I attempted the very same in my first year of college (in the UK, so about the same age). I only got as far as a memory manager, FAT16 filesystem driver and basic bootloader though so congratulations for making it so far!

Here's some great resources for OS dev, if you wanted to take this further (or if anyone else in this thread fancies a shot):

- http://wiki.osdev.org/Main_Page

- http://forum.osdev.org/

- http://en.wikipedia.org/wiki/Master_boot_record (MBR layout)

- http://en.wikipedia.org/wiki/File_Allocation_Table

- http://www.ctyme.com/rbrown.htm (full BIOS interrupts list)

- http://www.emu8086.com/interrupts.html (much friendlier BIOS interrupts)