Strictly speaking you probably aren't either. Steroid diabetes is a recognised condition in its own right. Usually it is temporary, but it sounds as though in your case the damage caused by the steroids was so severe that it is permanent. In terms of treatment, you are probably pretty close to a T1 (i.e. you don't make any of your own insulin).
It is simplistic to classify diabetes into just two types - there are many more. The ones that I am aware of are: Type 1, Type 2, LADA, eight different types of MODY (both LADA and MODY are sometimes called Type 1.5), gestational diabetes and steroid diabetes. It is just that T1 and T2 are far more common than the others. However, as Hanna said it really doesn't matter what it is called so long as you have a treatment protocol that works for you. Incidentally, although you are right in thinking that T1 is usually diagnosed in young people (often children), that isn't always the case. The oldest known newly diagnose T1 was 93!