The fact that you took action is what is important, no way to control the outcome. That's why it is SO IMPORTANT that people take periodic CPR classes, as you never know when it will be needed. Great job Travis.
You certainly tried everything possible. If it relieves your mind at all, CPR has a low success rate even in the hospital setting, and especially in the field. I have been doing it for over 32 years now, and rare is the case that pulls through. Even more rare is the case that survives and goes on to lead a normal life. Dont feel like you failed. It isn't you. It's the human condition and our limited capabilities to fight it when things get critical.