Happy birthday!
It’s really shitty when friends let you down on your birthday. I had a similar experience earlier this year for my 19th. I went home for the holidays (I’m at uni) and tried to plan a big night out to celebrate my birthday (I would be back at uni for my actual birthday though). Most of my friends ended up saying they were broke, or couldn’t make it for other reasons. I ended up cancelling the whole thing. I was really upset by it. I just ended up going to the cinema with my boyfriend.
I decided “screw them” and realised my uni friends were much better people, and spent my real birthday having a great time with them.
Moral of the story? Get better friends.