You are not alone. This is the curse of the destination wedding. Even if you offer to pay for everything, other people may not be able to go. It seems that the only people who can go are friends who are out of school and out of work, really old retired relatives or your parents. I think you're actually lucky to get your brother to go with you. Just understand, these people really do want to come and wish you well and they aren't trying to jerk you around. But they need to concentrate on their lives too. No matter what happens, you and FI will be husband and wife and that's all that matters.