It sounds like you're overconditioned, and like Lauraimes said, you'll have to cut out things like heavy oils and shea butter. That cream you're using might be too heavy for you, and not get absorbed since you're low porosity. Try a protein treatment! You might find it will help redefine your curl and re-add some volume. Here's a thread on a popular recipe you can make: PT recipe - as promised
So now we're talking your protein/moisture balance is off... but many curlies complain about lack of volume in general. Styling methods are important here... look up clipping methods, plopping, and diffusing techniques!