I don't tell anyone unless they ask because it really hurts if it is forgotten and I had a (either reasonable or mislead/misunderstood) expectation of something. Part of it is that I would like to once, as an adult, have a little sincere fuss made over me by the small group of people I call friends, but am hyper sensitive to the thought that other folks might not find me important enough to make a little fuss over. Not a real big deal, that would be too stressful, but something that shows they thought enough of me to care to do something special, even if it's a small nothing bag of cookies and an afternoon of their time set aside just for me kind of thing. It really hurts when people act in ways that show they completely forgot me, so why give them more opportunities?
As for a celebration, if it is an annual thing, it gets this "rote" feeling to it, feels insincere and is a whole different kind of uncomfortable. It was kind of awkward at work, when I worked in an office setting, because they had a policy of getting a cake and singing happy birthday and sending around a card for everyone to sign. You passed the card around in a folder from desk to desk, so the birthday person wouldn't see it until the "surprise" was revealed (even though they did it for everybody every year, so you knew it was coming). Since I was the secretary in charge of birthdays, if I didn't do it, it didn't happen. So it felt really uncomfortable the first few times getting my own card and ordering my own cake (my boss made me do it). I mean, what do you say? "Here is my birthday card for you to sign"??? "Put it in this folder so I won't see it until *the big surprise* at lunchtime"??? Aaawkward!, until they finally hired a second secretary who actually liked me and handled that job for me when it was my birthday. (She would always ask me quietly what kind of cake I preferred to make sure I liked it. Needless to say I returned the favor when it was her birthday!) On the plus side, I always got exactly the kind of cake I wanted
Now that I have a husband & children, we have a total of 3 birthdays and our wedding anniversary within 11 days of each other, so I just do "the birthday thing" for my son who is still little while my husband & I have a quiet dinner & movie together to celebrate both our birthdays & anniversary in one shot.