Hi,
You might actually be eating too little. Especially based on the physical demands of your job, your body might be holding on to every pound it can because it has gone into starvation mode. Try bringing your calories up and see if that helps.
Also, my doctor said don't worry too much about losing weight before the first fill. The body is healing and getting used to this new way receiving and processing food. Once you have your first fill, then you should start losing weight.
Hope that helps a little.