Hazel Levesque: How old is she? [hoo]

So, in the heroes of Olympus series, Hazel is introduced as a 13-yr old. But is she really?

Hazel died dec 17th, 1941 which is her birthday - her 13th birthday. Assuming my math is correct, she likely resurrected around the battle of Manhattan Ish, so her 14th birthday passed by the time SoN takes place. But that makes me wonder, if she died on her birthday, is the day she came back her new birthday?

I'm not sure, and pls correct me if I'm wrong, but how old is she during the son of Neptune?