I will try my best not to echo the prior posts, because I agree. Hormones are not magic.
They do some cool stuff, not all of it is visible.
At your age, the best thing is HRT will stop testosterone damage in its tracks, and that, rather than estrogen may make the biggest difference between you and many other transitioners. Also it will stop male bone formation and allow for some female bone growth, so you may get some hips (jealous).
No clue what will happen though. Your face will likely soften, most likely breasts, new skin, subcutaneous fat, less body hair, you will smell different. But even these changes are quite subtle, and it is the culmination of the whole package that makes such a profound difference, not just one thing or another. I really wish we could tell you more.
The weird thing is, you may not fully respect all of the changes like others will, because you will never get to appreciate what HRT will prevent from happening. You will just know life without that damage.
As for what I feel, I definitely noticed the lack of T more than the addition of E, especially at first. Now I barely remember what T felt like and I really notice the surge of an E injection.
Which reminds me, you may quite possibly have to swallow T blocker pills, just like I have to get injections (I used to hate shots. Now they are fun!!! Weeee!), but it is amazing what you will do for that peace of mind that transition can bring.
Best of luck.