Advice from a music teacher to amateur musicians: “You think the song is too short, the audience (almost always) will perceive the song as too long”. When you are an amateur musician, who sticks her out by performing on stage, you get instant sympathy, even without having heard a single note. If you play decently, people will enjoy your performance as well. But, because you are not (playing like a) famous rock star, patience / novelty might run out after a while. “Ah, she is going for another verse”.
Have the courage to keep it short.