I don't know if this is true for most people, but 'tomboy' isn't necessarily about appearance. I had long hair up until.....five months ago, varying from just below my shoulders to past my butt. Especially here in Utah, that alone pegged me as a girl. Wore dresses/skirts on important occassions and to church. Wore makeup on occasion, (when Mom forced it on me lol) and heels when I had to. Did dance as a kid and even in HS.
But there was no doubt in ANYONE'S mind that I was a tomboy. I loved to play sports, was a gamer geek, hung out with guys, etc. Nail polish and makeup were my natural enemy, and my go to outfit was jeans, t-shirt, and cowboy boots. Etc...
So yeah, I think you definitely can pass as a tomboy. Even if I hadn't looked at the picture. Its kind of an air about a person that makes them a tomboy I guess. And even if you had been wearing a bright pink dress in that picture, something about you gives off that tomboy vibe. At least to me.