Prednisone and weight gain :(

Hi there. I am brand new here and am hoping for some advise that I haven't heard/tried yet. I have been slim my entire life - never exceeding 110 lbs (only when I was pg and even then I lost it right after my babies were born). Well - I have recently (in the past few months) been diagnosed with adrenal insufficiency and was put on steroids. Unfortunately steroids are a HUGE weight gainer and I have to be on them for life. This 110 pounder (at the highest) now weighs 145 and can't seem to slow down the weight gain at all! I do Jazzercise a few times a week and I walk about 5-8 miles a week. I have been watching what I eat - sticking around the 1200 calorie mark and even taking the Acai Berry and I am STILL gaining!!! I am also bi-polar and this is not doing good things for my mood swings . I am a single mom of three wonderful little girls and I feel if I don't get self esteem back soon - I am not going to be able to be the mom that I want to be anymore. Has anyone else dealt with Prednisone weight gain before and been able to find any results... anywhere? The only information that I can find online is that people find relief after they go off the steroids. Well, unfortunately I will never be able to go off of them. My body no longer creates it's own energy and if I go off the steroids... it will slowly shut itself down.

Oh - ya... and I drink at least 8 glasses of water a day and try and stay away from sweets and all that good stuff. Honestly... I am trying so hard and it just keeps packing on! So frustrated ...