I haven't been sleeved yet, but I can speak to losing weight after pregnancy when you are already obese. My youngest daughter came as a surprise, and I already weighed 200 lbs at conception. I was terrified that I would gain the large amounts of weight had gained with my first two pregnancies 8 and 11 years earlier. Not only was I concerned from a vanity point of view, but more so for the well being of the baby, my own health and ease of delivery. So I was determined to keep the weight gain in check, but in a healthy way. And I managed to keep it to less than 20 lbs by eating healthfully (no empty calories!) and getting cardio in everyday. It worked! Weight gain was minimal and quite easy to lose afterward. And while I was still overweight, at least it wasn't made worse by the pregnancy.
Have faith that you can do this...you are strong and in control. I mean really, look at what you've accomplished so far!
Good luck and keep us posted!