I think you would be limited in what you can do physically which may make it difficult to get through nursing school. There are nursing jobs where with limited physical demands but they are not plentiful. As far as your mental health challenges you need to know if you are able to study and meet deadlines for one thing. Take a credit course at university and see how it goes before applying to a full time program. I think your chronic use of narcotics could possibly be an issue but not necessarily. However, if you were ever to make a mistake it would be likely the narcotics would be blamed, whether their use impairs you or not.