5.1″ is not short at all, rather, it’s normal for a woman.
You must learn how to develop a thick skin for such comments and let them pass by you.

I am female with 5.1 ft height and my fiancy has around 5.9 ft height ..I have personally no issue with such difference. But the thing that hurts me is sarcastic comments of other people on my height.. As they compare our heights and laugh and call me short all time which eventually hurts my self esteem and I feel like I am not right girl for that person. Please help.