Problem
Now that you have a good understanding of your market, it is time to go back to your prototype and refine it to fit in with your findings from the interviews. This is called the PRODUCT-MARKET FIT. Your product should be the one that the market wants and needs and will pay for it.
You will have to decide if you will stick to the original prototype, tweak some parts to fit into the market expectations, or change it.
A word of caution. At this stage, you should have a Minimum Viable Product (MVP). Watch the video "Making Sense of MVP" to guide your decisions.
In your own words, what do you think is an MVP and how will making an MVP be necessary for this stage of product development? Describe/illustrate your MVP.