Oh dear...
The age gaps between my close friends and I are generally more than this..
8 years between me and my bestie, I do sometimes have to remind myself I experienced things she didn't because I am 8 years older, but very very rarely.
Theres 15 years the other way between me and another v close friend, meaning she was entering the partying years of teenagerhood when I was a toddler.
I don't have that many friends exactly my age, but I am also struggling to remember how old many of my friends are because I generally know that they're 'around my age' or 'older than me' or 'younger than me' and thats it, (yes I am shit at remembering birthdays too, they all know they have to remind me, and I'll forget their actual age).
Once you cease to be a child, it really really doesn't matter. Their age is not why we are friends, its how interesting they are, do we share common interests and ideals, thats whats important to me!