I have always known mine. It was something innate, I suppose. After some research, I noticed totems fit people's personalities perfectly; so, meditate, understand yourself, your feelings, and where you come from. Then associate that with what you have observed in Nature.
You know what your totem is, deep down. You know what it is because its a reflection of yourself. You just have to look within yourself, then you'll find the answer to your question.