I transitioned after being on HRT for a very short time. My body loved the change in hormones and exploded with femme curves. I eventually could not pass for male and transitioned. Things went to hell and I detransitioned.
Why:
1) No support from work. I worked for a big box retailer and the management did not even tell the employees that I was transitioning. Talk about a big first day on the job! I was the center of everyone's attention and EVERYONE had to come and check me out. I was also sexually harassed on the job. They fired the employee but did not ban him from the store so he would come in and call me all sorts of names. Also had a customer masturbate while watching me work and ended up being escorted by a good guy in loss prevention whenever I left the store for awhile.
2) Threats. All kinds. Fun stuff.
3) An endoc that was 2 hours away who did not believe in blood work and was more concerned about being paid than my welfare. Local good endoc (who I now see) had a massive wait list at the time AND was not covered by my insurance.
4) Money. I was working retail making all of $11/hour. I barely had enough to eat each month let alone do anything else like go to doctors and get hormones.
5) Crumbling support. I do not trust others that much now and was even worse about it back then. My therapist, the only one I had come to respect back then, was retiring and between the crappy endoc, money issues, and a stalled name change on the fed level....
6) Could not get hired. I looked great. Carried myself well. Dressed professionally. And still could not get work anywhere doing anything, including other retail jobs.
7) Could not handle the opposite sex. I was hit on, constantly, by guys. Everywhere I went I was being checked out and hit on. Maybe for some of you that would be great but it freaked me out, badly. At the time I did not even entertain the notion of going out with guys. Today is a different story.

Oh and note: Wearing lesbian themed clothing and jewelry just makes them try harder.
8 ) Bad guys. Stalkers and other nutjobs.
9) Loss of my primary care physician. Yup, did not like the trans.
10) Depression. Spiraled heavily and quickly.
I detransitioned and swore to rebuild my life. Within a year I had taken on a new job and that led to another good job and then I went back to the other but at a higher pay and things have only improved. My insurance covered the kick butt endoc and I found a new therapist to write the letters that I needed rewritten which she did almost immediately.
Plans to retransition were derailed once by my being laid off. It was a post 9/11 world and the business did not scale back quickly enough and so I was shown the door. I then had to put in one year at the place I am at now before moving forward (was sure they would fire me and wanted legal ammo).
I will state that my going backwards gave my family ammo for not being too thrilled with my choice to transition again. they kept saying I was not happy the first time (they had no idea what I was truly facing back then and they still really do not. If my mom knew the details of some of the things that have happened to me in the last decade she would probably have a heart attack) and it took them awhile to see that I am happy now.
Today I am happy, healthy, and post op.
I have no regrets for the whole journey. I have learned more about myself and society and am a better person for it.