Similar situation here and my conclusion is that getting in shape requires:

-exercise

-regular sleep

-good diet

With an infant and a toddler on board I can maybe do two, but typically one.

If it's any consolation sleep deprivation prevents long-term memories from being formed, so you won't remember most of this.

In the first three months after my first child was born there was definitely something happening, but I wouldn't know - I don't recall any of it.