Possible? Theoretically speaking, yes.
There seem to be lots of plausible and quite intriguing theories of time travel.
Due to the nature of physics in the universe to make something irrational and completely inplausible become reality, I myself would not say that it is impossible in any way.
Quantum Mechanics/ and Physics have lately brought up some really interesting new options and theories to us.
Would I change anything?
I don't think I would.
I hate myself, and I hate my life, and I hate almost everything I can think of with deepest disgust and despise.
Yet, I would not know how to be any different, and I would not know what to change (other than as already suggested; to kill my parents)
I highly doubt that anything would ever make me feel better in any way, anway ._.