Aidan_
Some folks are just lucky enough to have names which go either way - Dana, Adrian(ne), Stacy and Tracy come to mind - while others pick a variant of their given name: Marie for Morris/Morrie, Dani/Danielle for Daniel and Lexi.
My original femme name was Maureen for a tall beauty I fell for in 8th grade and it has little in common with my male name except the initial. My sweetheart named me early on because she liked the name and said I looked like a "Susan" to her. I liked it too, so it has stayed with me for 35 years or so.
Now if you like opera, Aida or Ida could be good starters based on your real name. Try names of girls you admire, days of the week or seasons (Sunday, Autumn, Spring and Winter) or browse through a list of baby names. I didn't stay with my first name and I know of many who have used two or three names until they've hit the right one.
Susan