Can't help with feeling lousy in ketosis cos whenever it's hit me I feel really great and loads of energy. Sorry, complete opposite to you. Don't worry though, there are lots that feel the same as you.
Your first weigh in will be great, don't go worrying. I think it's cos when you first start this you don't quite believe you can get such great losses and consistently too. Obviously after the first few weeks you may not have such large losses but good, consistent losses none the less.
Good luck for your first weigh in, I can't wait to see the result now!