Even before starting a family, Brittney Castro worried that someday she might feel forced to choose between her career and her children, a dilemma to which many working parents can relate. So in late 2012, she left her job as a financial planner at an advisory firm and launched her own practice.

"I wanted the flexibility to have a family and not worry about losing momentum in my career or balancing a strict 9-to-5 job" and a family, said Castro, a certified financial planner and founder of Financially Wise Women.

Castro has a lot in common with many other female entrepreneurs. Women are starting businesses at a rapid rate these days, and many, like Castro, are partly motivated by a desire for greater control and flexibility in their work lives.

Of course, owning your own business can be a more sure path to greater wealth than working for someone else, and in many sectors women are still struggling to break the proverbial glass ceiling and achieve pay equality.

According to a study commissioned by American Express, women launched an estimated 1,300 new businesses per day last year, double the daily start-up rate for women-owned businesses in 2011. There are now more than 9 million women-owned businesses in the U.S., and they generate more than $1.4 trillion in yearly revenues, according to Amex.

While that sounds impressive, the sad reality is that most women-owned businesses are still small enterprises. Although women start businesses at twice the rate of men, only 2 percent of female-owned businesses break the $1 million threshold in terms of revenues, according to Ernst & Young, which holds a yearly competition and leadership program to help promising female entrepreneurs scale up their businesses.

The National Women's Business Council reports that only about 12 percent of women-owned businesses have paid employees.