Pretty Good, for a Woman in the Workplace

Here are the facts:
I am currently the only woman on my team of three at work.
I have never to my knowledge experienced discrimination because of my gender.
My boss' boss is a woman.
I have conversations with many older men (35 and above) in my company.
I am a small woman, under 5 feet tall.
I have a higher voice than some of the women in my company.

My feelings: 
Sometimes I suspect that they (not my managers, but other men) think I can't handle physical tasks. "Do you need help with that box?" Sometimes I do need help, but then I wonder if they respect me or not for needing help.
My managers rarely show strong emotions, such as sadness or stress-induced anger. Therefore, I feel that I am not able to show many emotions in front of them, for fear of being perceived as weak or pitied.
Sometimes I feel pressure to push through my tasks so that I stay under their radar and in good favor with them.
I wonder if they see me as a potential leader or only being capable of a team member role.

I don't always feel like I need to perform well because of my gender, but sometimes, I do feel that way. I have to prove that small women can do big things, before another small woman is disrespected.

Have you ever felt like you needed perform well to represent your gender? Share your story below or on Twitter.