So as of September 22 this year the Social Security Administration implemented a major change to how gender markers are set up. You no longer need proof of any legal or medical transition to change your legal gender. This means even if you're not on hormones or haven't had any kind of surgery you can get your marker changed. After 24 hours you can go to the DMV and apply for a new driver's license and regardless of your state it'll list your new legal gender.

You just have to go to the Social Security Administration and when you're filling out your application check the gender you identify as. You don't need any additional documents. You might need to explain the changes to the person who takes your application (mine thought I needed a court order and argued with me before looking at the new policy) but after that you can get it changed!

For more information here's the updated FAQ page with the documents you need based on your citizenship status: https://faq.ssa.gov/en-us/Topic/article/KA-01453

(also I don't think this changes birth certificate policies but please correct me if I'm wrong)