eeek! get her to check all of your references, and have other teachers read through it too, and see what they think? if it gets out of hand, take it further!
i know exactly how you feel...
for my A-level physics research paper on tornadoes (i was immensely interested, I'm doing a meteorology degree!!), i handed it in, feeling oh so proud of my achievement and certain i'd done well, to have it handed back with a big fat "E" in red on the front. I honestly nearly cried. I went to talk to my teacher and he said he thought I had just plagiarised the entire piece of coursework and lectured me about how that wasn't good enough. I then proceeded to, as calmly as I could given the situation, tell him exactly how much work I had put into it, and that I would like him to check every single one of my references, and put it through one of those internet things that matches it up to articles/journals/websites to check for plagiarism. I think he realised how serious I was being and took it back, checked a couple of the references while I was there. He then had to profusely apologise about the situation, and tell me how it was too good, and he honestly didn't think it possible for an A level student to write something of that standard (maybe cos I was so darn interested! My geography teacher said the same thing when I handed in my 10,000 word research report on hurricanes when the word limit was 2500 words...). He also said I shouldn't try to improve it because he feared I'd mess something up trying too hard with it! I ended up getting 100% and it's a good job too! My ex was there at the time and said he'd never seen me so scary XD
persevere, and don't let it get you down! if it's something you're proud of and worked hard on, it should remain that way, rather than be tainted by a teacher's opinion, who then goes around spreading rumours to the other staff...professional much?! i think not :P
(rant! sorry!)