Sex and sexual orientation are in the soul. They don't change over time. Changing them through surgery and hormonal therapy creates all sort of imbalances that deter advancement. The OP said they are transgender. Transgender is not the same as trans-sexual. Trans-sexuality is accepted but there is no word about transgenderism on any SS website of the clergy.
Being childless is no sin. That depends on who you are as a person. Not everyone is fit for having children. Those who do not bear them have other roles as guardians of society, teachers, etc. Generally, those who foster advancement in ways other than offspring. Here there is a sermon by HP Don about the organic state and social requirements: http://groups-archive.com/viewtopic.php?f=2&t=257