Christine – Moby Dick is about a tremendous fight for control by the human ego and the enormous Life Will – See - http://dreamhawk.com/dream-encyclopedia/what-we-need-to-remember-about-dreaming/#TwoPowers
But your meeting with the whale is fine, and it is saying it loves you. In fact it is a classic symbol of the unconscious, and it is fine to allow yourself to enter it unless you are frightened of it. If you do it will be the beginning of a amazing journey.
The injection is a way of saying that your conscious self, your ego, will be knocked out. So it is another way of entering the Life Will or unconscious. Then you are in the dark, and meet a dark figure – all signs of things arising from the unconscious. The gates are representing “A threshold, like that between conscious self awareness and our total experience - such a gate needs to open and close.”