You are almost never too far gone, and you are actually an excellent candidate for tummy tuck surgery with realist goals.
Review pictures of results from the surgeon you choose in order to verify your desired result is achievable. (Neil Gottlieb, MD, Philadelphia Plastic Surgeon)
Your pictures suggest the kind of starting point from which a great result should be expected.
You appear to have good skin quality and removing the excess skin and fat, removing some extra fat in the upper abdomen and pulling your skin tight should give you both the contour and the shape you likely had before your children.
Find a Board Certified plastic surgeon you like and trust. (Jeremy Pyle, MD, Raleigh-Durham Plastic Surgeon)
The next step is simply to get some consults. Don’t be afraid to ask questions until you are satisfied with the plan. (Ronald Schuster, MD, Baltimore Plastic Surgeon)