Hey there, I also like Devin for you, it's pretty androgynous if that's what you're aiming for right now, and masculine for later. I know several people with the name Devin, both guys and girls. As for your haircut, your current one I think is cool, but it seems difficult for you to see, but idk

. If I were to give you my opinion, I would say that you would probably look good in having a cut that is short on the sides like yours, and a bit longer on the op (More than just that one piece that you already have). Although again, I don't know what you're looking for specifically.
Clothes wise, with khakis, you could totally wear t-shirts and stuff. That's what I do for the most part. Khakis are like jeans where they work with most everything. Although I find that wearing button-up shirts make me feel ultra manly hah. Just do what makes you happy and confident of course.
Good luck with everything!
-Grayson