How can a hospital put false diagnosis's on your medical record, and how to get it off?

I just had a baby girl. I was in the hospital for one week, I had pre-eclampsia. I had a few pain meds while I was there. So I dont remember everything. Well I dont think some of the nurses liked me very much. I say that because the nurses were asking me questions and I was polite with my answers. When I got the discharge instructions for my baby, there was FALSE diagnosis's on her paper for ME. One said I never recieved prenatal care until 22 weeks. Thats false I went somewhere else for my care. I did mention that. Also I only have a eighth grade education! Are people serious I have a high school diploma. Also that was put on my medical record is that I have psychartiac (lol I made a typo) problems. I know I need to get my medical records from my all the doctors. I also did some reasearch on free legal aid to see if I have a case. How can a hospital put things on your medical record without ANY proof? My next question is HOW can I get this **** off my medical record? I look at it like this it takes at least twenty mintues of talking to someone to see if there intelligent. The nurses are only in your room for what ten minutes? Thank you in advance for your help.