You are a good guide here since you are undergoing the changes. Presumably you have initiated this process because you feel that you are really not the gender you started off as, and so your notion of personal identity was quite complex even before the process got underway. Clearly we change all the time, and sometimes so radically we come to believe that we are quite different from how we were in the past. You are in the interesting position of perhaps feeling that you are finally approaching becoming the sort of person you "really" were all the time, and you are thus in the best position to report on how your feelings make up this changing self-perception. Self-identity is clearly far from a simple notion and nothing evidences that so much as your course of action.
Read another response by Oliver Leaman
I am transitioning from male to female, along with physical changes I notice changes in my thinking and emotions. Am I the same person or am I becoming some one else? How do we know who we are and do we become different people over time?