first of all I should tell you that learning masculine and feminine in French is not that tough, there are rules which make them easy to learn.
about your question I should tell you that the speaker matters. For example being female all adjectives becomes feminine, no matter you talk to a male or female.
I will now clarify it little.
in this sentence: "Nice to meet you" , who is saying this? who is nice of meeting the other? yes, you. So because you are female you should say: Enchantée (F)