How long have you been eating so little? If it's been a significant period of time you might want to mention this to your doctor so that he/she can run the appropriate tests to see if there are any medical problems that have come about due to this. You can probably start by telling your therapist about your concerns, they will likely refer you to a Pdoc in order to make sure your physical health is okay and they will work on your emotional stuff. It sounds like you might be suffering from some disordered eating if you feel fat after eating so little. Don't worry, you're not alone and there are plenty of options for you! Take care.