To add to the previous comments: In a resume type of text I would not use contracted forms: I've -> I have etc. We will work on -> The method I use includes...., going forward step by step. ... language, that: no comma. I feel this is a rather audacious statement to make about yourself. Alternative: I pride myself in being a non-.... possess a mastery... I would use: Not only am I a master of the language,

"I've perfected my knowledge of French HAVING LIVED and STUDIED [1] in Paris, France and FOR [2] more than 16 years living in 5 Latin American countries. You will be hard-pressed to find a non-Latino, French teacher with the depth of understanding and fluency in this beautiful language, that I have. Not only do I possess a mastery of the language, but I simply love it." [1] You have lived and studied in Paris which is the reason why you have sound French knowledge. The use of the perfect participle phrase 'having + past participle' denotes a completed action. It is similar to "ayant + participe passé" in French. [2] We use 'during' with events (during the day, during the concert, during my birthday party), but we use 'for' with durations (for two days, for several months, for a long time). I hope that helps! Keep it up!