PhD research, research doubts?
Don't stress too much for your proposal. In all likelihood your PhD will evolve as you progress. As you said you've been reading a lot. Don't be surprised if there is little material to reference. After all, that is the point of doing Ph.D. research: you will be adding to an area of knowledge which at present is little understood.

My Prof once told me that in year 1 the student should be guided, in year 2 the student finds their feet and in year 3 the student leads their supervisors

And yes, speak with your supervisor. This will answer your doubts and display you are really commited to being rigourous.