How old is Teddy Lupin at the end of Deathly Hallows?

I don’t think so, teddy was born around the time that Dobby died, and the battle wasn’t far after that. So, teddy would have had to been 6 months after the battle. Then at the epilogue it is titled 19 years later. So teddy would have to be 18-20 depending on his birthday. I was confused in the book because the way JK Rowling wrote it sounded like he was 15 or something