You don’t really need to transfer academically, quite frankly. First of all, Fordham is an excellent school. It’s in the top 100 national universities; on a grand scale, it’s pretty prestigious in its own right (just not like an elite university).
Second of all, international studies is close enough to international relations for your purposes. Undergrad is a time to get breadth of study, not depth; you don’t need to focus on something so specific in undergrad. That’s far too narrow - and besides, before you concentrate on that you need to know the foundational basics of international studies, like comparative politics, economic policy, and culture. Most of your major classes are going to be core classes and breadth requirements anyway, and at most you are going to get to take 2-3 electives in a specialty area within your major.
There are already a couple of classes that would encompass national security in the course listing, including International Communication, Analysis of International Politics, Conflict Resolution, UN Peace Operations, Introduction to Peace & Justice, U.S. Foreign Policy, Anthropology of Political Violence, etc. Economics is a huge part of national security these days and there are many classes on that. Health and environmental concerns are also key to national security (see developing nations where health crises or environmental disputes can create conflict) and you’ve got access to classes like Environment & Human Survival, Epidemics and Development Policy, Intro to Environmental Studies, and Hazards, Disasters and Human Experience.
Think foundations. Think “If I wanted to study national security as a graduate student, what would I already need to know/understand in order to do that?”
Why are you unhappy at Fordham? Is it something that is likely to be solved by moving universities? You’ve been there only two months - maybe two and a half at best.
Big Division I sports teams tend to be found at large public flagship universities. Do you come from a state with a big flagship with D1 sports? Otherwise, unless your family is wealthy enough to cover the full cost of attendance, those might be cost-prohibitive for you. (If your family is wealthy, then you have many options to choose from.)
Here are some prestigious privates with Division 1 sports and/or big sports cultures and some version of an international studies/relations major:
-Georgetown, of course - probably the best place you could go for this, if you could transfer into SFS.
-Boston College
-Lehigh
-Duke
-USC
-Tulane (Int’l studies concentration within their political science major)
-Wake Forest (no major, but an international studies minor)