I read somewhere that when you count everything, it's actually 13, but I've written it out twice and still got 12...
1.) Charms
2.) Transfiguration
3.) Defence against the Dark Arts
4.) History of Magic
5.)Potions
6.)Herbology
7.) Astonomy
8.) Arithmancy
9.) Ancient Runes
10.) Muggle Studies
11.) Care of Magical Creatures
12.) Divination

If that helps...you might be able to see if I missed anything....