Not much a fan of the post processing on these. The original images with some basic touch ups would look like they would be acceptable to a family member as a favor, but the PP detracts from the photos in this case. A lot of people preach, "if it doesn't add to the photo, then it shouldn't be a part of it/in it." I live by that when I shoot/edit.
You're on to something with the composition/poses of the shots in that they cover the bases for engagement photos. I'd get a little more creative with your subject matter when its there in front of you in person, not at the computer. The best engagment photos in my opinion are the ones where the couples really look, go figure, engaged in each other. They're pictured interacting in some happy/fun way.
Honestly though, not a bad go at it for the first time. Would you be willing to post the originals for us to see?
~Tom