Getting into YCombinator is a means to an end. If YCombinator is your ultimate goal, reconsider where you want to see yourself and your startup.

Get out and build. Get customers. Change the world. The time and energy spent being nervous about this is not productive.

I don't doubt YCombinator will help in tremendous ways (I also applied), but it's important to keep pushing forward in spite of whether you are invited for the interview or not.