Aerospace Engineering here. Junior, 20 hours left. I've been co-oping (like internship, but you switch out school semesters and work semesters alternatively) with Jacobs Sverdrup, a contractor for NASA. I work with multiple contractors all at Marshall Space Center and NASA employees. It's kind of fun, but at the same time boring. We're (well, I'm not there this semester, but they=my group) working on requirements right now for the CLV which will be replacing the Shuttle. Next semester I'm supposed to be working on the Upper Stage engine and they supposedly will have prototypes ready by the time I return.
Anyway....
What classes are you taking? Alot of people are saying to **** it up, and you're saying you want to change majors. I must be new to this, but even as a declared engineering majorin his Freshman year, most of your classes (except the intro to "..." engineering class) will go toward nearly any degree at the Freshman level. In my opinion, if you're having this much trouble right now you seriously need to rethink your whole academic future. It sounds harsh, but seriously, what did you think college was going to be like? Alot of people say that classes get easier when you get into your respective major, but that's not always true. My classes are getting intensely agonizing, however, I stick it out because I know that unless I'm a professor the odds of me solving these kind of problems in the real world are about 1 in a million. You'll use some of your general engineering knowledge but the majority of your work will be OJT, on the job training.
Having said all that, give it a little more time. Don't cram all engineering specific classes into your schedule next semester (which I imagine can't be anymore than 1). Alot of people switch majors. I have 3 times, and none of the previous 2 were engineering majors.
If you want to know how most people here feel, check
http://www.caraudio.com/forum/showthread.php?t=181524&page=3.