This tread has drifted aware from the original topic. Yes, you can have good result transitioning in your 30s or later. That does not mean it does not work out very well for some people. But that does not necessarily mean that age is the factor.
HRT is only one aspect of transitioning. I am a little concerned when peoples top goal in taking HRT is physical changes. It just seems that seeing it that way will set you up for disappointment. Starting HRT to improve how you feel, and help with dysphoria was the primary reason for me and any physical changes were secondary. It is the primary driver when talking to my doctor. If we ever changed any dosages, the first question was "How do you feel?", not "How are the physical changes?".
Knowledge is power when it comes to HRT. Yes we should be under the care of a doctor, but having the knowledge on standard dosages, ideal levels, and the pluses and minuses of the different forms of medication are very important. Approaching it like if you were a doctor learning about the process. Being a self advocate with your doctor is a super important thing. In particular in this tread I saw two things that make me suspect that HRT is not optimized. Little physical changes from HRT, but the reported E levels seemed low. Lose of sex drive, where T levels are below the level to measure them. HRT is about balance, and the balances seem to be off, which can cause poor results.
However, even with all that, HRT does not always work out for physical changes. It is something that many of us were warned about (hopefully by your doctor), that results can vary greatly, and that can happen at any age. And that as we get older that HRT can have less of an affect, but even that has great variation as is evident from this tread and many people on this forum. That was the purpose of this thread, was to give people an ideal of what HRT can do in your 30s (or later). And for many it works well, and for some it does not and I have lots of sympathy for those cases. Hopefully this thread will give someone thinking about HRT in their 30s a balanced view of this.