I use the word "inventing" because of its Latin roots. It literally means "to come into"--think veni, vidi, vici; that first veni is the 1st person singular perfect active indicative of invenio, invenire, inveni, inventus(mas.) -a(fem.) -um (neut.) (whichever gender you prefer!). The "in" is just the prefix for in or into. So literally, "come into."
I would agree with you, I despise the term transition. I dislike classifying myself as a transsexual, transgendered, transwoman. I'm just a woman who is inventing her own gender expression for the first time, and it is some 12 years overdue.
I don't know about gender identity affirmation. It is kinda long, but if you like it use it. Use whatever you like to describe yourself. People may argue that its too confusing, but those people are to obsessed with categorization--a thing I have come to despise. We're all unique, and while most of us on this forum may share similar experiences, we are not the same people. In reality, we have nothing in common with eachother--unless you want to say we're all human--I'd agree with you there!
meam propriam femineam inveniam. (Its been awhile since I've done Latin, may be a bit rusty!)