Its a tricky situation! In some ways, age doesn’t matter - you can still love each other just as much, and still have a great relationship.
But there are some things that might become problems.
He’s quite a lot older than you. In terms of maturity, either you’ll end up trying to act too old for your age, or he might be quite immature for his age. Acting mature doesn’t seem like an issue - but you should really enjoy your teenage years.
Does your family have an issue with the age difference? I would definitely suggest talking to them before you make any decisions. I know it doesn’t seem fair for them to choose who you date, but they will have good opinions about it, and if they are really against it, you don’t want to tear your family apart. I had issues with this when I was your age, and I ended up fighting with my family AND my boyfriend over it.
There’s a lot you’ve missed in his life. His 18th, his 21st, he’s already of legal age to drink and smoke and go gambling. You might want to look at which of the above hes involved in - and whether or not he’ll want you to join in too.
Above all, I suggest asking a bestie who you can trust to give an honest opinion.