Actually...contrary to many fans stated, the author here made the right count. In season 1, Otabek was 18 at the beginning and was 19 in GPF Barcelona (it was in December right, x-mas and Viktor birthday). While that year Yuri was still 15 from beginning to end of YOi season 1. So their gap was actually 3 yrs 7 mo
Look it up on yoi wiki fandom or watch the series again.
The show refers to him as 18 in episode 11... I even screen grabbed it.
https://drive.google.com/file/d/0B-xbjlHNssVZUVJtMVJkTjd6SDQ/view?usp=drivesdk
I was going to say this was a flashback to the previous year, but it's actually stated by Victor in episode 10 too. So yeah, Otabek is 18 at the GPF in Barcelona (though he might have his birthday soon after or something)
The author got the ages wrong. If Yuri is 18, Otabek would either be 20 or 21, depending on the time of year. Their age difference is a few months shy from 3 years.