How do you determine whether you are OCD about something?

A recent question was asked regarding things you are OCD about. Some of the answers made me think about the stuff I do out of habit, thinking it is normal.
For example, my room is always in a mess, but I always have the bookshelf tidy and the books in order.
I always try and keep my clothes facing one way in my wardrobe, with the hangers also facing one way. These are things I do without even considering that it’s not normal… is it normal? Or just habit?