its probably because most of the people who apply for the 2 year plan don't think about doing it midway through college. they've already taken the test and provide their score. this gives a good baseline since they will all have taken the test at the same time. you probably will score much higher on the test in college because your skills will have improved.
also, if you live somwhat CLOSE to a school with an NROTC program, go there and see if you can establish a cross-town enrollment with your junior college. it is not difficult, I have seen it done several times. participating in that will GREATLY increase your chances of picking up an OD scholarship, and if need be a 2 year scholarship.
you should never plan on getting a 2 year scholarship. they are much rarer and more competitive than the others.
I recommended to you on a different thread to download and review the ROD. Look up the table of contents and check out the various scholarship options. It will give you a good idea of the various entitlements that come with scholarships.