I'm struggling with this too. The few boys/men my age I'm able to spend time with act very awkwardly around me because they're not sure how to treat a trans person - just like I'm not sure how to treat a cis male

The ones who are comfortable with the trans thing see themselves as gatekeepers to the world of masculinity - they keep trying to school me in the ways of the modern man. It's frustrating - I'm not trying to become authentically male. Like you say, it's just more stereotypes. I'm trying to be authentically me, whatever that means. I appreciate them trying to help, but it just adds to the anxiety and those "you're not one of us" vibes.
I think the secret is not to worry about fitting in. Everyone does, cis or trans - and everyone's drawn to the people who seem like they don't. If you can act like you're secure in yourself and your identity, even if you're faking it, people will respond. Don't question whether you fit in - take it for granted that you do. I find that helps with my anxiety. It also helps to scream inside my head, "these are people, not men!" because when I focus on their maleness, like you I find myself fleeing conversations, the anxiety gets so bad. Usually to throw up in whatever appealing bush I can find.
Don't doubt yourself. You're wonderful the way you are, and people can see that whether you come across as masculine or not. Spending time with other men, you'll naturally pick up on their mannerisms - you probably fit in better than you realize. Just try not to worry about it. Easier said than done, I know, but it'll all come naturally in time.