If I read this correctly, you have the "reduce the size of the enclosing part" option selected, but since there is a small amount of white space between your field and the bottom of the body part boundary, that small white space remains after the slide and shrink takes place.
If one of your fields does not have a visible boundary, resize it to extend down to the very edge of the body. Then, the slide/shrink should shrink the entire body part.
If that's not possible:
I haven't tried this myself, but perhaps you could create a single calculation field set to return a single space character if the other fields are not blank and is blank if the other fields are also. Size and place this field in the offending white space between the other fields and the body border. Set it to slide/shrink like the others making sure that no part of this field overlaps any field above it even by one pixel.)
I think that'll work.
Thanks, it worked!