If you are having doubts about it then it's probably not the best idea to get into something with this guy if you are so unsure. Two years isn't a big age gap but sometimes in teenage relationships, it can be. Sixteen seems quite young to some people so to be in a relationship with someone of that age, you might get a bit of stick because some people are like that, it's nothing that you should take seriously. If you think that you can get over the age gap and if you really like the guy then I don't see the harm in trying, like you said he will be seventeen in August, thats not too bad and the fact that he is actually only one year bellow you in school, isn't that bad either.