the girl next door - welcome! I do not think your efforts were in vain. You saved lives, there is nothing about saving a life that isn't important. There are human beings who were given a chance at life because of your efforts.
Although the blood rules are a bit different now there are still a lot of witnesses, I would even say a majority, that view accepting fractions and pieces and parts as bad as a whole blood transfusion and simply will not do it. I know, I'm married to one.
Imagine if the arguments and discussions you had with those parents were actually with your spouse about your own children. It's not easy but it is worth it.