You must be very frustrated, I feel for you. Listen, you do not need a wealth of calories to boost your metabilism. I do not agree with your dietition because what she said does not make sense to me. You can easily take in more than 1000 calories daily before three months. shakes alone can help pack on the pounds if they are coupled with a little food daily.
Listen my friend, you may need to start exercising, and if you are exercise you must do more. This can help to boost your metabolism and get that scale moving in the right direction. Once you do, then you can see if you start to lose. If you don't it means you are eating too much or so little that your body thinks you are starving it and is hanging on to every pound. I am an RN and not a Registered Dietition. I strongly suggest that you speak to someone new to she if maybe your dietition missed something. I am not saying he or she does not know what they are doing, I think sometimes situations warrant getting advice from more than one professional. Also, write down what you are eating every day for at least three days to ensure your daily caloric intake is accurate. Bring your lists with you to your dietitian, he or she will appretiate it.
Best of luck, hang in there, a resolution is surely around the corner!