I haven't read the replies above. Just saw OP's question, and thought I'd give the view from a new airline pilot. I took a job at a regional airline in August.

Counting my initial class and the class before and after, there were 40 new first officers, and 5 of them were women. All the women made it through and got qualified. I had a look at the seniority list for my base, and looking over the 20 FO's immediately above me on the list, 3 are women. So I think around 10-12% of the pilots at regional airlines are women. Some came from charter/freight jobs and some came from flight instructing.

Since hitting the line, I have flown with about a dozen captains, 2 of whom were women. They seemed happy with the career. One has kids at home and one doesn't. My airline has five bases (domiciles) and each has a chief pilot. Two of the five Chief Pilots are female.

So although everyone has heard horror stories of grouchy old captains who behaved poorly toward a female FO, these days I think everyone has worked with enough female pilots that even the oldest and grouchiest has gotten used to it and won't be unpleasant. Over the next five years, the number of female captains will be closer to 10% (at the regionals at least; and ten years from now at the majors as well) so it should be a complete non-issue.

There are probably facebook groups of female airline pilots where you could ask about their experiences.

One good thing about an airline pilot career is that, once you are hired, there is very little opportunity for you to be discriminated against for race, sex, orientation, etc. My previous career was in business, and there, promotions, raises, etc. are subjective (the bosses give promotions and raises to who they want / who they think are the best). This means that a boss who thinks less of the female employees can (deliberately or unknowingly) slight people's careers based on their personal characteristics. But union airline pilots all move upwards at exactly the same rate, regardless of age/sex/race/where they live/what college they went to. You will get the same raises every year as your counterparts, and provided you don't screw up (and most don't), you will become a captain at the same time as everyone else in your initial class.