How excited are you about other people's birthdays? I'm not, so I am not surprised when I am not in the birthday loop. You are very concerned with how other people treat you, and you feel left out. I always felt left out, too, but then I realized I was leaving myself out. I had no clue how to participate. Maybe you are in the same boat. I decided to stay out and not bother learning a culture that is not natural to me. Your decision may be different.