I already have a MacBook Pro, is getting a MacBook air overkill?

I am Pre-Med student and bought a 13in MacBook Pro when I started college in 2011 and I got an iPad 2 as a graduation present. I find that I don't use my iPad all that much because I find it difficult to type on in class and my MBP is so heavy that I hate lugging it around. Another reason that I hate carrying it is because I spent so much on it that I hate for something to happen to it in the abyss of my booksack, I've already had to replace the screen on it once, I don't want anything worse happening to it. So, I thought the solution to my problem would be an 11in MacBook Air. I know they're not as heavy and definitely not as expensive.I feel like it would be easier to carry around and use when I'm at school and it would be easy to move my notes from my the MBA to my MBP.

I guess my main question here is: Am I being silly? Will I really enjoy having the MBA and have an easier time using it while I am at school? Or do I need to just suck it up and carry this big heavy thing with me?

I would really appreciate some feedback!