I am torn on this decision. Before we had our child, I was 100% tell to our child. Now that he is here, I go back and forth between tell or no tell. I do lean more towards telling b/c I don't think it is something to ever be ashamed of. We are so fortunate to have this technology. Once that child arrives, it can really change the way you think. It just so happens that our donor has the same blood type as mine, so that would not be an issue. What I do regret is who I did tell that DS was donor conceived. I have no regrets that our family knows, I have no regrets that our friends do not know (with the exception of my best friend). I do regret telling my OB and our Pediatrician. So, I think it is great that you are no tell to everyone until you decide what you tell your child. On the other hand, the people that are tell to everyone, it appears that it is a non-issue and no one ever brings it up.
Bottom line, I know it is important for you and your DH to sort this out before conception, but like others have said, once your child is here you both may do a 360 turn around.
Good luck on your journey.