Amanda, thanks for your question! I am a women working in a STEM field, so I applaud you for pursuing what you enjoy. I am not sure which particular schools may give more financial assistance to women in STEM fields, but if I were you, I would start looking for particular scholarships for women in STEM. Often times, individual, non-school specific scholarships are quite specific in terms of to whom they will grant their scholarships. You may find a scholarship for women who were born in your state or county that plan on going into the field of mathematics but is not specific to any school. At the same time, once you find some schools you are interested in, there will be school-specific scholarships that are specific to women, women in certain fields, etc. The number of scholarships are never ending, you just have to find them. A deep-dive google search will probably give you some good leads.
Just a super quick search online produced this link to start with:
I'm sure there is more where that comes from. Good luck!
Like most full scholarship programs, there are a few rounds of interviews and a number of applicants, but I would review the requirements and past applicants experiences to better prepare for the process.