I'm not sure if I'm cut out for this

It's great that you are self-aware. If you take the attitude that these are things you need to change about yourself, then you're on your way. If you take the attitude that there's nothing you can do about it, then forget it because you're going to have a tough time in nursing and you should find another career plain and simple.

However, I would like to encourage, rather than discourage you.

Issue #1 - Nursing is not necessarily a thankless job, Most people have manners and do indeed say thank you. Some even send cards, candy and nice notes to administration. But there are going to be plenty of patients and families that no matter what you do it isn't going to be good enough. I work in a tough environment myself and have to listen to whining complaining patients and family members after I've just broken my back trying to make a difference, or even in fact rescured them from a potentially dangerous outcome. At the end of the day if I know I've worked hard, given my personal best (and that varies from day to day), then I have to find satisfaction from within.

Issue #2 - Again, it's good that you're self-aware that you have this issue. Maybe you can talk it over with someone as to where it comes from and that might help you overcome it. Don't worry about female doctors, (however, we are at a time for the first time in history female med school students are the majority), worry first about your female instructors, preceptors, charge nurses and managers. From Day 1 in nursing school you are going to be directed, taught and judged by female instructors because 90% of instructors out there are female (not really, I'm making that up, but male instructors are rare because the pay is so low) and trust me they can put up on negativity right away. You have to learn to accept delegation from females plain and simple. You have to accept that as a student and new grad you're at the bottom of the totem pole and chances are females are going to be directing you. I've always had female bosses and right now my bosses boss is female as well. In fact there is only one male nurse manager in my facility.

I also work with several female interns and residents and it's not like Grey's Anatomy. Give respect and you will get it. It's easy.

Issue #3 - Math is something you must conquer in school, but in the real world we're lucky to have pharmacists and machines do our calculations so once you get through school you should be fine. Most schools have labs and tutors available should you need it. Many people buy into a self-concept "I'm no good in math", and it becomes self-perpetuating. Change how you talk to yourself saying "I have the intelligence to learn math and be a competent math student" rather than defeat yourself.

Good luck!