Maybe you can look up men's haircuts for your length of hair, and see what you like. I think having a more masculine haircut will help a lot. Not short, just styled in a way typical to men, perhaps.
Also, this will probably be stupid, but I think working out a bit will help you. If it's something you can do and want to do, I reckon gaining a bit of muscle will help, your arms from what I can see, can do with a bit of muscle. I mean I'm not judging you, because my muscles are practically withering away, haha, but yeah.