Research is an iterative process and rarely progresses in a perfectly linear fashion from choosing a topic, to finding sources, to writing the paper. As you engage with sources, it is probable that you will need to revisit your original topic idea.
Having an expectation of what you hope to demonstrate is natural. However, be wary of cherry picking or only acknowledging sources which agree with you. Research should endeavor to follow where the evidence leads. As such, you may discover that the evidence contradicts your original assumption, that there is not enough data or scholarship, or that you will need to modify your original research question.
It is common to encounter hurdles when researching. Even experienced researchers confront roadblocks. The trick is to be persistent but flexible: to try a variety of search terms, follow up on leads, read, reflect, read some more, and revise.