the most important thing is to realize that you can't control others opinions. you should appreciate the people and places you can find that respect your avatar as an adult.
but i have to say there is nothing creepy, wrong, or against the sl rules just by using a child avatar. only involving them in adult situations is. most child avatars in sl have no intentions to, they are there to relive their childhood through g rated roleplay.
my avatar has a flat chest, small hips, and is 4'3 tall. i consider her as 8 years old and i dress her and treat her like she is. i even use an anime head just as you do! anime was a big part of my childhood. and even now the anime i watch are those aimed for kids, i don't care for fanservice or blood. and i'm not interested in making my avatar fit in and be a realistic adult either, life is too short to care what others think of or assume about me. sure i can't visit adult lands, but i was never interested in them anyway.