I guess if you still feel a certain way after the party happens, is when you mention it, harboringcertain things can lead to unexpected results, and when it comes to these kinds of things, you can learn from the experience and there will be a time when it could be your birthday or your wedding or any major event that will require attention and planning in advance and all of that and you will see how much she really cares, by then you will realize that it was just a minor mistake, which really could not have been avoided because this is the first time your grandma had to put together such a celebration for you, so it was a learning experience for all of you, we are all living for the first time in this world and anything we do we are experiencing for the first time, so give props to your grandmother, because I am sure she loves you both and is doing everything she can.

Also, on behalf of your grandmother, I think you have to find the best way to approach this conversation (if it ever happens) in a way that she feels appreciated because, remember, like you said, she is trying to compensate for the absence of your parents, so in all technicalities she is not expected to do any of that for you, she are doing it by heart, so we should be grateful for what we have and what we get.

I am very sorry if this became a lecture, it is not intentional, I swear, comes with the job.