I can fully understand and relate to the feeling of being completely ready and prepared to die, but there's that little part of you that just won't do it. It means that some part of you is not at peace with the process, or some part of you is not ready just yet. That doesn't mean that you don't want to die, but rather that you don't necessarily want to die. Death is a delicate topic in the end as it is an absolute, it is the end of everything and possibly the beginning of nothing. Sometimes being suicidal amounts to hating everything about our existence, but sometimes being suicidal doesn't necessarily mean you want to literally die at that exact second. Something is causing your survival instinct to be strong. Take some time to reflect on how you feel about life and death, And how you feel about what may come after death.
if you are in fact completely set on suicide try to rehearse the process in your brain each day and think about what it would feel like to leave this World. normalizing your own death for your brain, and bringing a sense of peace and well-being associated with the process of dying will help soothe your nerves when you come to that choice.