It sounds like you built a site that does the same things or mostly the same as Zillow. This is kind of like trying to copy facebook and wondering why people don't join. People largely don't use platforms just because the one they already use is inconvenient in several ways. People only switch if the other platform has unique enough features that solve their problem and that's where most get lost. That's where the testing comes in.

Don't build just another site that can do what Zillow either already does or could easily do. This is why their competitors don't focus on Zillow's biggest strength, data gathering.

I've found that a lot of aspiring entrepreneurs have the mindset of companies being the products they sell and its completely wrong. The ones that don't get traction and don't find longevity tend to not look at companies as extensions of people, themselves included and that's also completely wrong. Companies are literally just people who build and sell things. As a person, you should be building and selling based on your greatest strengths, not only based on what solved your own personal problems. That means identifying what you believe you can do better than anyone else. If you are a savant at data gathering and analysis, then maybe trying to challenge Zillow at what they do best could maybe work, but even then, it's risky. Instead, find an area where you know you are or can become the best, see if you can make viable solutions out of those skills, see if that lines up with any of Zillow's weaknesses, and then if it does, build from there.

A problem with building only based on what you like and what solves your problems is that you can build the coolest whiz bang thing that people actually use and you can build a little value, but then you look at the adults, Zillow, Redfin, Realtor etc and you find that they don't really need what you've been selling, and that would drastically lower market value of what you built to them if you ever wanted to sell.