Very nice question, a lot of wrong answers. Struggling with this question does not mark you as a transsexual. Many gender variant persons can feel a significant intensity to present full time as a woman. Almost all of them are fine being men but want to present differently, and this desire can be very strong to the point that they will transition but usually keep their male reproductive organs. Transsexuals are born as transsexual and they seek to be either women or men depending on how their brain is organized (but always not congruent with their bodies). They experience their bodies as defective, like a birth defect and will in all circumstances seek to correct this defect and move on living in their correct sex.
Transsexuals by and large do not re-transition. Research into outcomes has shown that 80% of those that transitioned are happy with their lives and simply move on being who they are.
Re-transitioning occurs mostly with gender variant persons who are high on the intensity scale but are not transsexual. Sometimes they actually seek surgery but regret it later. The cases are few and far between.
Transsexualism is not a choice. Transsexuals would give almost anything to not be who they were born as. It is a medical congenital condition that requires to be properly diagnosed.