I have been struggling with my weight since I was a junior…

Good Morning!
Probably the most important first step in a lifestyle change is recognizing that something has to change, so congratulations for making the decision to change.
Your dietitian was not incorrect in saying that chances are good that you will need weight loss surgery, because statistically speaking 98% of people that have >30lbs of weight to lose will never keep that weight off. It is impossible to tell at this point if you are in that group or a 2%'er.
The most effective and healthy way to lose weight and keep it off is to make a lifestyle change, where your approach to food, exercise, and prioritizing yourself take precedence over the other things in your life that always seem to pull you away from what you want to do (work, family, studies, etc). You need to reset your mind to always make at least a little time each day for you to do the things to help with your weight loss. That means, taking the time to plan out your meals, so you have healthy snacks and meals available every three hours. Taking the time to get some exercise 4-5 days per week.
I would recommend getting Bill Phillips' book "Eating for Life", which does an excellent job of spelling out a lifestyle change. There is a good chance, if you get in the habit of eating healthy, balanced meals every three hours, and exercising, that you will be able to lose the weight you want. With that said, at the end of the day portion control plays a big role in your weight loss as well.
Eventually you will have to shrink up the amount of food you eat, in order to lose the weight. If you have a major problem with being hungry all the time after meals, then you should consider weight loss surgery. A Lap Band/Realize Band is a less-involved surgical option that does an excellent job providing portion control/hunger control. Gastric bypass is also an excellent option for long-term portion control, and has the added benefit of preventing some of your calories from being absorbed.
I would definitely try to make a lifestyle change first. Again, some people are able to lose the weight with proper eating and exercise, and you won't know if you are in that group or not without trying. Eating for Life is a great place to start (I have no affiliation with Bill Phillips or his products, btw).
Good luck,
Dr. Dan