Interesting thoughts, especially you saying the lines in your hands changing... i was wondering if i was just hallucinating because the lines in my hands are changing fairly quickly. There are some very strong transits taking place where the planets are going retrograde and hitting natal degrees 3 times(especially strong with pluto conj. natal uranus then going retro back to it in awhile), plus the partial eclipse on my natal moon. Anyway the point is yes the planets do have a strong influence but we make the choice on how to use them.
The charts can show a great deal about what we may have been and done in past lives. Edgar Cayce used astrology for karma and past lives readings as well as his gift. This gets into all kinds of theories on reincarnation and spirituality so this is just my own theory. There is a certain amount of fate purely because the energies that strongly manifest will be... well attracted (but not exactly). The planets set the stage and we play the parts, one of the reasons we evolve the way we do is a result of the planet's foundation in our mind/soul at the first breath. Therefore they can show us our progress based on what we still need to learn.
IMO the future is like a cone of possibilities leading up to the point of the present, and there only one real "reality" which also leads into the past expanding ever outward again. The past experiences can then be used to create other potentials. The potentiality of each individual incarnation's reality depends on our charts and our choices. It also depends on the amount of experiences and lessons we have undergone in our countless lives. If you see the relationship of your actions on thier reactions, and that all reactions you face are due to actions you understand karma. The very reaction of our births was based on ours and other's actions, we then use the energies for our own paths ever guided by our higherselves.
Life is but a game, and is filled with tests that we only pass or fail... once we are finished with the tests we ascend(or are liberated or enlightened, whatever you prefer). We are never really alone and there are times when "external" factors help us in times of need. We also are givin as many tests as needed, it's ok to fail we all do sometimes just part of life. Everyone is unconciously working together in perfect synconicity in the ascension of the Earth itself and the evolution of our higher(real)selves, "The universe is unfolding as it should" (not sure who said that). Well at least that's what i think, still working on my view of the the "truth".
I know this, we can not control everything that happens in our lives... but we can change how we respond to it.