Cherlyn - i'm so sorry for your loss. You really did all you could. And it was very brave of you to share this story step by step. This thread will help many people.
The decision to intervene or not is based on experience, but also intuition and gut feeling. But ultimately, it's up to that little chick, her health, and will to live that determines the outcome. i'm going through multiple hatches right now and have had some tough times. i helped one little baby out after it pipped and didn't zip and think i should have waited a bit. So the next pip i left alone. The next day when it hadn't zipped i went to check. It was fully formed but dead. i guess i didn't help soon enough. Argh!
All you can do is the best you can do. You went above and beyond for that little chick, so please don't feel bad at all. Thank you again for sharing your journey.
Colleen