It is appropriate to use the phrase "my findings" in this context, even if you are reporting on the results of an opinion poll conducted by others. By analyzing and interpreting the results of the poll, you have arrived at your own conclusions and insights about the topic, which can be referred to as "your findings".
Therefore, it is perfectly fine to say "in this essay, I will describe my findings and express my opinion on the subject of the project."
However, it is important to be clear that the data you are reporting on is from an opinion poll, so you may want to mention this in your writing to provide context for your findings.