One thing that I would like to add to what the others have said is the impact of lack of sleep on weight loss. You have a newborn so you it is only natural that you aren't getting enough sleep and there isn't really anything you can do about that. Add to the lack of sleep, the stress of going back to work and all that means for a new mom.
Give your body time to adjust to all it has been through. Keep eating healthy, drinking plenty of water and working out when you have time. Relax and enjoy your baby and don't put pressure on yourself to lose the weight....that only adds more stress and might lead to emotional eating.
Believe me, as a mom of 5 (including twins) I know how discouraging it can be to not have your body spring back. But it will happen if you keep following the SP program of setting goals, healthy eating with occasional "treats", daily exercise, drinking water, support and
tracking. Be patient. It took you 9 months to gain the weight (and as all new moms learn....most of it isn't the baby)....give yourself 9 months, at least to take it off.
If you don't love your body now, you won't love it after you reach your goal!!!