i don't think she looks that masculine to be honest. I mean, yes, you can sort of tell that she's made of "the tougher stuff" so to speak, lol, just like you would imagine a heroic/action woman. And I think it fits Megan to the bone like that since she is the ponies big hero after all.
they always commend her of being strong and clever.
I think the reason one might mistake her for looking masculine in the first shot is because her hair is tied behind her back so it looks like it's really short. ^_^
otherwise i think she's a good attempt at megan, and sewing clothes can be very tricky! so I comend you for managing her "weirdo green jumpsuit" as I like to call it. hihi. ^_^
only thing I miss on it is the little pink heart on the front!
you could always use some sort of textile glue and simply glue a little pink heart on her chest.