Let me add myself to the group that thinks you need a new doctor.
First - unless you are very small and VERY inactive, 1200 calories is way too low. You might lose weight for a while, but eventually your body is going to scream "famine!" and you'll slow things down even more.
I hope I can post this link -- http://www.nafwa.org/harrisbenedict.php.
This is the Harris-Benedict calculator. The key to making it work is being COMPLETELY honest about your activity level. What you will learn from it is what you need to eat to maintain your current weight. Then drop down no more than 20% below, for three consecutive days. On the fourth day, go back up to 5-10% below. Keep this up -- by increasing calories on the fourth day, you'll keep your body from panicking.
Also, add weightlifting to your répertoire. Muscle bumps your metabolism, fat doesn't. If you're at a "Y" (I think you said -- forgive me -- brain cramp) you should be able to get some help to get started.
I'm 51 and I'm doing this successfully (and I have a lot more than 40 pounds to lose!
Good luck and let us know how it goes.