Do you have a picture you can post?

They'll grow as fast or as slow as you allow them to. If you want the plant narrower, cut the bottom-most leaves (if that's something you don't find aesthetically displeasing. A mature Aloe vera will be about 3' tall and about as wide. If you want it to grow smaller, I'd suggest getting rid of it and getting a miniature aloe. You could start over with the pup, which is fine, since you already know what the end result will be (it will get too large and you'll have to do the same thing) but you'll have the fun of growing them up (and perhaps giving the mature one to a friend who does have the space).