You didn't mention whether the soy milk was sugar-sweetened, or just had sugar in it. Soy milk has some natural sugars, which are fine. The refined sugar used for sweetening is what we try to avoid.
I'm not sure I understand your logic about eating sugar as a way of avoiding sugar cravings. To me, it sounds like your plan is just to keep eating sugar, but eat less of it. Limiting the amount of refined sugar you eat is certainly better than not limiting it, but if you eat that way, you wouldn't be on phase 2 or even phase 3. You haven't told us much about yourself except that you're 20 years old, so I don't know if you need to lose a lot of weight or whether you're just trying to make some better choices. So it's hard to say whether you would reach your goals, eating the way you have described. It might help you in the long term, though.
One thing to consider is that many people here, including some people with tight schedules, strict budgets, food limitations, and other practical challenges, have found ways to make SBD work for them. Some things you might consider are bringing food with you (in an insulated lunch bag), or eating before your events. You might also consider trying different foods that are on the "foods to enjoy" list, to see what you like. You are really the one in the best position to decide what you want to do, and how to do it. Best of luck!