Hi Mandie,
This is a very good question. When I got my physics degree in undergraduate college, I felt very out of place especially in the more advanced classes when I was the only woman. I wondered - should I not be here?!? I got very good grades and loved the classes, but it was hard to be such a minority. And when I was even younger, in 9th grade (in 1985), I was told by an astronomer that women cannot do physics so I really should not even try. Luckily, I was also told by many men and women teachers that I should become an astronomer if I like math and physics and many men and women told me that I could do it!
Throughout getting my graduate degree (Ph.D.) I ran into many relatively minor issues being a women. Mostly I feel that as a woman many people assume I am stupid until I prove that I am smart, whereas it seems that if a man says something we assume he is smart unless he proves he is stupid. So that is hard. And I have had colleagues tell me that they are glad to know me because otherwise they would think women can't do physics - this was said to me in 2001!!
Like the other women who responded, when I am doing only science I am often the only woman in the room. And I have to be careful not to make a judgement about myself and women at those times. Mostly, I really enjoy the people I work with - both men and women. And mostly I don't have any issues with working with primarily men. But this could be because I shifted my job to do more education and outreach activities and less science and now I work with lots of women scientists and educators. I feel very fortunate both in most of my interactions with male and female scientists. For the most part, scientists care about evidence and if the evidence is that I can do science then it doesn't matter that I'm a woman. But I think it is important to still look at this issue because it certainly is not yet an equal society, though we are getting there.
Laura