I had the odd realization today that everyone I've been a CP or beta reader for (with the exception of 2 people) are now agented. And while I'm genuinely thrilled to see people I care about finding success, I can't help but feel left behind. I think it's natural to try and beat that out of yourself, but if you're going through something similar, just know it doesn't take away from your happiness for your friends. Take a deep breath, okay? It's fine to feel bad for yourself from time to time as long as you don't dwell on it.
For me, my first reaction is usually a tad pessimistic, but I don't let things keep me down for long. I've been alive long enough to know everything does work out eventually. And here's the thing, just because no one picks up your book does NOT mean you're not a good writer. All it means is that it's not the right book at the right time.
I'm finally at the point where I feel confident enough in my skills (and I get better with each book I write) that I feel like finding my right fit for an agent WILL come. Eventually. For the time being, I'm focusing on things I can control like starting on the next idea, learning how to compile a strong query package, and improving on writing dynamic openings to my stories.