Like the other posters, I am assuming you are machine quilting this, not hand quilting it.
I would just press the top and backing and get it as flat as you can. You don't mention if you are doing this on a rack setup where it is more difficult to load an out of square top. But it is not impossible. Do not take the quilt apart to redo. Just do the best you can and I am sure she will love it. Swirly curvy quilting can work in a lot of fullness. Don't attempt to SITD, it will only amplify any inconsistencies in the piecing and straight like quilting will work fullness into furrows which will give you even worse tucks and puckers. An all over meander or similar type quilting, fairly densely done will help to reinforce the quilt and hide a multitude of problems.