But very often I may not recognise my inner Self. I do not know whether the voice I hear is the inner voice or the outer voice, and this is extremely confusing.

I fully understand. But if you get a teacher who is a realised soul, you can go to him for help and find out if what you are doing is correct. Or if you do not get a spiritual teacher, please go deep, deep within and see if you get a voice or a thought or an idea. Then go deep into the voice or thought or idea, and see if it gives you a feeling of inner joy or peace, where there are no questions or problems or doubts. When you get this kind of peace and inner joy, you can feel that the voice that you have heard is correct, that it is the real inner voice which will help you in your spiritual life.