If the person in question was looking for a serious relationship, it's normal that she didn't want to follow up. Long distance relationships never work out.I went on a dating app called Veggly in November and I managed to meet someone great straight away. However, after two dates, she decided not to see me again because I'm planning to leave the UK again this year and go back to Chile.
Have you ever tried to start a FB group in Chili for vegans wishing to meet up? It's very often through meetups that people can join in various activities and help you meet other vegans.
If you only want to date a vegan, it's obviously going to be far more complicated to meet someone. I don't know what the vegan scene is like in Chili but I'm sure that you could meet many women in your age group is you were OK to date an omni.