Fin is a hormone blocker that primarily helps patients retain what they currently have (though I have seen many cases where people have regrown a substantial amount). Min is a stimulant that will decrease time between hair cycles and, in many cases, thicken/regrow hair. The goal is to ensure that you are halting recession in place so that you do not continue to recede behind the implanted hairs in the hairline.
You are starting from a great situation and have the ideal hair characteristics for a transplant but that doesn’t make you immune to continued balding. If I were you, I would really dive into the research and speak to my physician to put a preventative plan in place so I wouldn’t have to use more of my finite donor on the future.