Thoughts on my Birthday Party

So, last night, some friends and I went out to celebrate my birthday. I love birthday parties, and have been planning mine for about a month. We had dinner at The Keg (I love steak) and went for some dancing at the Bier Market afterwards. I've been putting my outfit together for weeks, and was super-pumped about my pretty dress and hot shoes (even if I do now have a massive blister on the side of my foot). All of my favourite people who didn't live in another province, have an exam, or a funeral, were there. Overall, I had a great time - I drank too much, had amazing food, danced, felt awesome, and was way too loud chatting with my friends.
There was just one thing.
A lot of people who said they'd be coming told me within the past week or day that they couldn't make it, and some said they'd make it and didn't show up. I totally understand that things come up and people have other things to do, but many people didn't a)have any excuse, b)tell me myself that they weren't coming, but instead told a friend to tell me, and c)didn't show up at all, no word as to why. It just left me feeling a little down. I am reasonably close with these people, and really would have loved to celebrate with them.
It just left me feeling that I'm not important to them. When I tell someone that I'll attend something, especially a birthday, I make it a priority to be there, or at least have a darn good reason why I can't and show them that I feel badly for letting them down. Isn't that normal? I thought that's what people did.
I don't know... I think I just really wanted to be peoples' top prority, especially for the one night I've been planning for a month in order to celebrate a special day for me. Is that unreasonable?
BUT, the people who did come were ones that I really wanted to be there, and they made it a fantastic night for me - even if I am lame and went home before 1am. I'm glad they were there to celebrate me and make me a priority!