Hmmm, I dont think the decision people will come out with will matter to u as you said you dont want people opions on the matter, so thats clearly saying you basically made up your mind already, however I will comment on both.
If he really does love you and you love him, then tbh it would really make no difference to be engaged now or in 3 years or so, however dont get married till ur 18 maybe older and the youngest.
But there's there fact does he actually love you? I dont kno ur full story however based on to wot ive seen with mates etc, lots of my girly mates wen they were u age back in the day :p dated 18 yr olds etc, and they said they loved each other and lasted 9-10 months, did I love you, marry me and wot not, then they would end. So tbh id be almost suprised if it did work out, but this isnt most cases, it could work out and you could be very happy. Which I wish you are.
So, if it is love it wont make any difference on engagement age(however dont actualyl get married till ur a bit older *as stated above*) and beware it could just be words and you could be very hurt. It may seem perfect now.... But alot can happen and at a younger age things can matter alot more