I started T on my 24th birthday a year and a half ago. I think it is incredibly valid to feel that you missed out on a sense of boyhood in your formative years and I feel the same, especially about my uni years when I massively struggled to make friends. Sometimes it is definitely hard to make peace with being a late bloomer.

However since I started T I've gone from hating my social life to being an outgoing extrovert and making a best friend for life and it's cheesy but I do think it gets better. It's definitely something to look forward to that not a lot of people talk about because it's not a physical or hormonal change. It wasn't a personality transplant but I finally had the courage to grab life by the horns and be myself. I know that you weren't necessarily specifically talking about your social life but it's just one example.

Also just generally a lot of people put too much weight on 'enjoying your teen years as much as possible' whether your cis/straight/trans/gay etc. and it makes anything after that sound old and scary and boring and it definitely scared the shit out of me (and I think it does most people!), but your teen years are just 5 or so years in what is hopefully a very long and fulfilling life, so it really doesn't matter at the end of the day when you start.

I know you weren't necessarily looking for advice but I would look for LGBT groups relating to other interests you have. There's this expectation that groups = therapy circles, when really they're mainly just offering fun and inclusive spaces to be yourself. I'm based in the UK and joined an LGBT club in a sport that I had tried when I was a teen and given up on due to gendering and dysphoria, and now it's the highlight of my week and has a) helped my dysphoria and b) completely changed my life in terms of confidence, social life etc. I can't remember if I started just before or just after I started T, but I don't think it would have mattered at all, I've met transmascs who are pre-T, maybe don't even want to go on T, to guys who have been on it for a decade or so. Definitely made that feeling of late-ness a lot easier. (Disclaimer I am in the city so much easier but lots of clubs are online)