Awww.. Im sorry for your experience

If the temp and humidity was correct then it was not any fault of your own. Most of us don't cut eggs until after the first pip. Some cut sooner. Some don't cut at all. An umbilicle cord being wrapped around the baby is not extremely common but it does happen. The smaller babies may have had something go wrong during development. Maybe the mother was not up to size and health? If not then try not to le it bother you too much. It sounds like you did what you could. The film and thickness of the fluid also is not right. Something was wrong with the eggs from the very beginning.