In Islam there is no such thing as age barrier when it comes to marriage. When our prophet Mohammed (pbuh) married Khadija, he was a 25 year old single man while she was a 40 year old divorced woman. Then when he married Ayesha, he was a 55 year old man while Ayesha was 12 year old virgin girl..
So go ahead and marry the girl if you want.. All the best