Hi, sounds like you're going through a bad patch! The good thing is that deep down, you know that you can't let things slide and that you need to tighten up your control and keep yourself well. It does get very boring, and for myself, I find I keep tighter control when I don't think about diabetes too much, and just relax into a routine - just like brushing my teeth in the morning and before bed, I inject before I eat and before bed. When I can keep the disease in a small part of my brain and confine it to a routine, it doesn't take up so much of my life!
When you were pregnant, you managed brilliantly - probably because the fact of being pregnant was more significant than having diabetes. If you could keep your HBA1C at 6 during pregnancy, you can do it now. You titled your post 'Depression', and maybe you need to talk to your GP about the way you are feeling, especially if you feel that things are really out of control. Looking after a toddler is demanding and tiring, and you may feel that there are too many things to juggle with, so you put yourself and the diabetes at the bottom of the list, but the reality is that controlling your diabetes is the key to managing your life and being stable enough to cope with the demands of caring for Oscar!
I hope things improve for you soon - instead of telling yourself that you have 'failed' on the days that you don't get things right, try and tell yourself that you'll do better tomorrow. Good luck.