I've seen lots of women change careers, some in their 20's, some in their 30's, and even more in their 40's and 50's.
I'm in the medical field, and the opportunities at my hosp are terrific. You get in at a job you are qualified for now, then they will pay for you to go back to school for something else. You owe them 1 year after you get your degree, but then you take your new knowledge and can go anywhere. I've known lots of people who have gone into MBA programs, nursing, radiology, resp therapy, physical therapy, psychology...
What I tell my kids, is what my mom told me. Find the thing you like to do, then figure out a way to get someone to pay you to do it... Happy Life...