What to do when my girlfirend doesn't want me to farm?

SO Ive been dating this girl for a little over two years. These two years I have been going to school for Civil Engineering (about 1.5 years left). She already is working full time in the medical field, a great job, but not quite enough to support us both. We have our whole little life planed out;graduation, job, house, marriage... the usual; but all dependant on my education. I really love her and her whole family and have no objections to the life we have planned, EXCEPT: I recenlty got an internship in Civil Engineering and hate it. So I started looking for something else. My grades dropped and now I'm behind a little in school becuase I have lost interest in anything to do with engineering, which really frustrates her. She keeps stressing that she will not wait forever to move on with her life. I have always wanted to be a farmer, having grown up on a dairy farm. My grandpa sold his cows (I was 10) when the EPA decided 100 years of manure was too much.... SO now I found a way to get into dairy farming again. I knew my grilfriend would be less than thrilled about it (working 24/7/365, the stink) but I figured if she really loves and respects me she'll go along with it. After all, it'll be my (and my cousin's; who will be my partner) job and not hers. I know farming is a way of life, and its the life I want, and always have wanted.. I just don't think she knows what its all about. She was never raised on a farm. I brok the news to ehr last nigth that I wanted to talk to her about the situation (how I can possibly start farming) and she flipped out. Didn't let me get a word in edgewise. I thought I could explain my plan and maybe she woudl see the light. I think she equates engineering to money and farming to broke, and I wanted to explain the cashflow of it all. I don't care about money as long as I cna pay for a house a table ful of food. Anyway... Any suggestions?