She's grown a ton since her first senior season, and it's pretty amazing how well she has adapted. Her competitive costumes are still very girlish and young-looking, and can really make her body seem that way too, but in her Sailor Moon EX at WTT you can see that the girl has got curves. She probably isn't finished growing, but as long as she continues to adapt well (as she already has), she's going to be fine.
I think this is true, to a certain extent. Growing up and becoming an adult means plenty of distractions, both in the world around you and in your brain. Stress, anxiety, insecurity, pressure, etc., all begin to feel more and more difficult as you become an adult. Evgenia seems to be very, very good at coping with this shift, and I bet Eteri plays a role in managing it and sheltering her as well. Evgenia is also lucky that she has experienced her "coming of age" in the pre-Olympic years, which has given her time to mentally acclimate to her status of best in the world (Yuna Kim, too).
Yulia, for example - even if she hadn't had major jump/body issues after Sochi - probably still did and would've experienced an abrupt, scary mental shift after the huge burst of fame she had at Sochi.