Doing mine the other way around....identified some interests, constructed a research question based off of that (without knowing the answer before hand), used the key words in my research question to identify the topics covered in my lit review, collect and code literature, write review.
As you go through literature, you will be able to see the gaps, conclusions, claims, findings, disagreements, calls for more research etc. Thats when you are able to put the different parts of your review in conversation with one another in order to steer the reader to your research and how it fits into, extends or takes a different view of the current debate.
As a rule if you are having problems with your research question, alter the key terms or alter the data analysis. I cannot tell you how priceless this book is:
http://www.amazon.co.uk/Destination-Dissertation-Travelers-Guide-Done/dp/0742554406/ref=sr_1_1?s=books&ie=UTF8&qid=1405778482&sr=1-1&keywords=destination+dissertation
go to amazon US for more user reviews.
If you want a quick and fast description of their lit review method (which I am using) check out this blog post (the site is excellent too)
http://getalifephd.blogspot.co.uk/2010/10/six-steps-to-writing-literature-review.html
Cheers