@Pandawanka I don't know. This manga likes to dramatisize height a lot so just wait till something is mentioned. Cause when they were expressing their doubts they never really talked about age, just how gloomy and whatnot she is...but then again for the gay couple they didn't mention homosexuality being the problem either, they were just shy.
Whatever. Don't act like you haven't seen 3000 year old dragon lolis in mangas before. The one thing you learn from reading a lot of manga is that age never correlates to appearance.