Rather than trying to bring together multiple themes, a good research topic explores a single narrow point in great depth. When you are trying to write about someone like Freud, whose work has already been the subject of thousands of books and articles, the obvious general points have already been made, and therefore don't need to be researched.
The point of research is to add a very small original contribution to what we already know about Freud. What this might mean is looking a some one very small example he gives of operation of the pleasure principle, and do a detailed historical analysis of it. For example, Freud talks a great deal about the role of religion in the second chapter of the book. Could you investigate how specific late nineteenth century Austrian practices of Judaism or Roman Catholicism might have shaped his views of religion?
Also, as part of a research paper, you should look in Jstor or Google Scholar (not regular Google) for existing research on your topic, so that your work responds to what has already been said rather than just replicating things other people have already done.