I'm not familiar with the space in the slightest. My guess is if you can't raise a seed round in this market, you either don't know how to do it or your business is not promising enough.

Have you filled in a YC application? If you send me that I can probably spot the problem very quickly. Email is gomox.ar (with the free Google email).

We applied for YC 2017 but didn't get accepted. I don't know if we still have access to the application we submitted.

You usually get a copy in your e-mail when you submit.