As much as we try there are still huge discrepancies in the number of women versus men in STEM fields. There are huge number of studies on this and why women leave STEM fields and what can be done about it and there are more published every day.
An interesting look continued gender discrimination in these fields came out in Proceedings of the National Academy of Sciences (PNAS) last September. What these researchers did was send resumes of a potential undergraduate lab managers to a few hundred professors at top universities in biology, chemistry and physics departments. The professors were asked to rank the candidate (named either Jennifer or John) on hireability, perceived competence, if they would be willing to mentor the candidate and what starting salary they should be offered. Across the board "Jennifer" was ranked worse than "John" regardless of the gender, age or tenure status of the faculty member. Even though the resumes were equivalent the gender bias meant that "Jennifer" was hired less often, with a lower starting salary, and fewer of the faculty members were willing to mentor her. For more in depth analysis of this study and its implications check out the articles from New York Times and Discover.
Numerous groups have resources specifically for helping women in STEM. The American Chemical Society (ACS) has a Women Chemists Committee with a bunch of resources (including a Travel Award for conferences specific to women). They also have a Women Chemists of Color program, but it doesn't look as extensive as WCC. The Association for Women in Science (AWIS) has some great resources as well (Career Center, STEMinars, networking/mentorship, etc). MentorNet has been working to pair mentors and protegees in science and engineering fields and is especially for women and underrepresented minorities. There are groups out there that want to see you succeed and want to help you, all you have to do is ask.