Hello!
I'm also back to sw after the birth of my 2nd baby who is now 4 months old. I think you're being very hard on yourself! I tried slimming at about the 2month pp mark, and failed miserably because it was just too soon. Now though, I lost 7.5lbs in my first week!
You don't say if you're breastfeeding, but that can really impact your hunger levels (not to mention hormones, lol).
Enjoy your new baby. The weather is getting nicer, so going for walks always helps with feeling more positive and healthy. It'll all fall into place!!