There is nothing wrong with teaching her to stop whining!
Some dogs just believe that it's all about them. I personallly would not have suggested getting any dog while a full time student living alone--but now that you've got her, I expect you can make it work! You don't have to pay attention to her all the time, and she needs to learn that. The exercise seems adequate to me, and make make time for some special time before you hit the books. And then you need to teach her that she can't get your attention any time she wants it. Not unlike a whiney child. My dog more or less understands "go lie down." If he's bugging me, that's what I have him do. Go lay on his bed.
I live alone and work full time, but when I'm home, it's pretty much George time. There are times, however, when he drives me NUTS and that's when he is sent to his bed (where he stares at me until he falls asleep).
Depending on her size, that may be too much food. George weighs 64 pounds, and he gets half the amount you're feeding, plus treats. He also goes about 2 miles a day.