So I've been looking for a place to share these two tips I've discovered for DFAB people who want to look even a little less feminine pre-T. Sorry if they've been discussed before.
1. Eyebrows - just thickening your eyebrows with an eyebrow pencil will de-feminize you more than you might expect. Don't go overboard, just fill them out a bit and make sure they're at least as dark as your head-hair.
2. Hairline - I somehow passed as male at my last haircut and the hairdresser offered to buzz my hairline, and I was amazed at how much it made my whole face appear more masculinely shaped. Basically you want to get rid of the hair at your temples, even if you're too young for male pattern baldness. Look at the hairlines of males your age to get a more detailed idea of what you're going for.
These might not necessarily make you pass better, but they've definitely made looking in the mirror a thousand times more bearable for me (especially the hairline thing).