@sziib,
Listen, my school (57 years ago) had a Spring cut off. I was sent to kindergarten at the age of 4. I didn't turn 5 until May, just before school ended. At age 5, I was in Grade 1. After 3 weeks, and only because I could read the 1st and 2nd grade books (Dick, Sally and Spot - stupid, repetitive books), I was sent to grade 2. So I was 5 in grade 2. Really bad idea for lots of reasons (math, social development, etc).
The reason, though, why I'm telling you this is that not only was I basically 2 years younger than everyone else, but I was tiny. Kids didn't want to play with 'little kids'
It all turns out okay because you adjust - become the class clown, the smartest, fastest, whatever. Overall, it evens out. It's all just how you look at it. Or don't look at it.
It could be a lot worse. You could be an orphan. You could be living in Yemen. You could be living in a war zone. You could be blind.
I don't mean to make light of your feelings, because I do know, firsthand, what you're talking about. What I'm trying to help you do is to put it in perspective. It's only a big deal because you're making it a big deal. As time goes on, nobody usually asks you how old you are or why you're older than everyone else.
This is something that you've taken to heart and I'm suggesting it's not that big a deal, so maybe look at it differently.