As the story unfolds, I am starting to see where your SO is coming from. While I do not necessarily believe that he wants to break up with you, I will be perfectly honest and state that I believe that he's being wise and frank with himself about the direction your relationship needs to take, and you would do well to imitate him in this manner. If you two are talking about marriage, it's only right to count the cost. You are a lovely young woman but I'm going to give it to you straight: if you were a man, I would be counting the cost, too, and would perceive some concerning deficits on your part that would cause me to hesitate in considering marriage. This is not because you're a bad person - not by any stretch of the imagination! However, it was living alone for two years that demonstrated to me how much money management is truly not a joke. It is not to be taken lightly that you shop before you pay a bill or that you yourself notice an alarming dependency on him and your parents. The fortunate thing in this situation is that you have the self-awareness to recognize it, and for that you are to be heartily commended.
Simply put, you need to move out. This is not about saving money anymore. This is about you learning how to be a good steward of your own life, to take ownership of your responsibilities and to discern the difference between needs and wants. In an earlier post, you mentioned that you travel or like to travel or can travel, something to that effect - and in the next sentence you said that you're a full time student. Why is a full time student traveling? Girl, hit them books!
Finally, I would be remiss if I didn't explain further as to why I stand in agreement with your SO. I know that my opinion will not be popular, but I see no problem with him stating conditions for you to get married. I am currently in graduate school and I can tell you that the pursuit of higher education is absolutely, positively, no joke. Some of my closest friends are in medical school and again, medical school is absolutely no joke. Some people took issue with the fact that he's talking about your financial responsibility, yet wants to enter medical in one to two years time.
ManeVixen, he is right to start thinking about this now. It can take about a year and a half to get all that stuff together - studying and taking the MCAT, lining up letters of recommendation, figuring out what school you want to go to... it is a very time consuming and EXPENSIVE process.
I know someone who applied to medical school for three years in a row and didn't get in.
Again, he is right to think about this now - he could apply and not even get into any medical school, and then what?
What I am seeing is that your SO has taken care of you but now reality is striking. If I had a man that took care of everything financially and we had a good relationship, I would want to get married, too. But you both have been living in a dream world and it's high time to wake up. Part of that will be moving out and gaining your own independence, and the other part will be doing as the women in this thread have suggested and have a serious talk about your relationship and the expectations for it. Stick to the 2 week move-out date that you set up. As Hopeful said, this is a turning point situation, but this experience goes far beyond the implications of your relationship. It has everything to do with your personal growth, which will directly shape your relationship. I truly wish you luck in whatever you decide to do.