This is my opinion.
No, it is not weird to like a girl 2 years older than you. My boyfriend is a year and a half older than me (not that you care). You dating an 18 year old is only going to be come a problem is when you decide to do things with each other (if you get the drift) because you are still a minor and she could get in trouble for it. If you really like each other, go for it but don't get too into it until you turn 18 because you could get her in trouble.