I love your work. And do not listen to people when they criticize your art. As an artist you have the freedom to do whatever you like and if you want to draw people the way you do then don't let others stop you. Embrace your style. I love it, personally. The great thing about art is that there is no wrong way to do it. Keep doing what you love
This looks like it was inspired by Rob Liefeld's infamous terrible anatomy: [link] or [link] or [link] I love your artwork and particularly your use of color and how well you shade, but the anatomy here is definitely troublesome. I really like the design on the surfboard and the choice to make Rainbow Dash a surfer in general.
Very nice job. One comment described her waist as too little, but I think it works. This is a very good example of exaggerating anatomy to get a specific artist effect, which in this case appears to be Dash as the lean, cool athelete. The baggy pants and tied bikini top were an inspired choice for her.
Oh and I really like your painterly digital brush work. It's not easy to make rough lines and loose swatches of colour like that look good.