HI justme,
I am not Cathe and I don't have 3 kids
BUt I am the same height as you, I weigh a little less(not much) and I have a 7 yr old.The only one I have has of now.
I have often wondered the samething as you.I have stretch marks on my stomach, proof that the skin is not the way it use to be.First when she was born I got back into my prepregnacy clothes.I was also only 17.Makes a difference when you are really young.Then I went to college met my husband and packed on 15 pounds.I found Cathe started working out and it seemed over those 2-3 yrs everything went right back to normal again.My stomach did get relatively flat.
Recently I have gained about 7 pounds.Within the last yr.So it seems like the pooch is back to haunt me.Somedays when I look at my belly I wonder if I could ever have muscles that you can see. I can also remember being sick(maybe hungover:+ )and after not eating my stomach was just like a wall.I have also been looking through my BFL book and have noticed some of the transformation.Most of the ladies have stretch marks in the before pitcure and in the after pitcure there mid sections are awesome.
I think anything is possible.We are all different so no one knows how long it will take.Grant it, after having 3 children it maybe harder then just having one.I also think that we need to spice up our ab work every now and then.The plank work in the new series are awesome.I haven't done enough of them to notice results yet.
The other thing I would think is to reduce body fat even futher.As women we tend to store any fat we have around our mid section and thighs.I feel the best when I am around 122lbs.I weighed yesterday and I was 129.5}(
I don't know if I helped you much and it would be nice to hear Cathes point on this.But when you said you have been working out for as long as I have,have a child whose 7,your height and weight.I was thinking,that's me!Good luck to us both! The only thing is, you will get your flat belly, so will I and then I will get pregnate, while your not!
Good luck,
Lori