With the current photo the dress looks fairly long, not too short. But it's taken from your head, so that might be an impression and your dress may be shorter than it looks in this photo.
About the reason why it is not the same size in top and bottom, I have my ideas. If you measure them now, are they the same size? I ask because sometimes we can do small errors which propagate quickly. I had this with my handmade skirt, an erroneous approximation at one centimeter finally gave an error of almost 10 centimeters.
I think the reason of that impression is that your "middle" body (waist and a bit higher) is more circular than your lower body (when we consider only an horizontal layer seen from high) then the cloth is wrapping your body circularly at middle, and more elliptically at bottom which gives that impression.
About the line between shirt and skirt part, that's maybe due to how you did assemble the parts. What I would suggest in that situation, is to use that kind of technique:
http://www.barthfashion.org/icours/ctrabattue.gif . That way, the cloth itself will not have any distorsion caused by some residual hem.