Help!

How should I quilt this beast, I mean beauty.  Actually this darn quilt has turned into a beast. It was super easy to cut and piece together.  I am SO glad Heather wanted little white window frames, love them!  It has been sitting on the bed in my craft room for weeks. Heather has been so patient waiting for me to quilt it. Last night I showed her this darling little block I made for a new quilt I just started.  She said, "I can't be happy about another new quilt (third one since the beast has been ready to quilt) until you finish my quilt".  So I made up my mind that I would do nothing else until this beast was ironed and pin basted.  Oh boy, 3 hours later!  While I was ironing I noticed that the sashing is way "loose".  It's like a different size than the blocks, what the heck!  It's even rippling on the edges.  How does this happen? Then I made my quilt sandwich, three times, and finally figured out that the back is 2 inches smaller than the top.  And just last night I was bragging on myself that I am sooo good with quilty math! Serves me right, gosh dang it!  I had to rip it apart and cut a bigger piece.  Anyway, I'm struggling with how to quilt it.  Please advise!  I will let Heather have the ultimate say, as long as It's straight line and not labor intensive. Ok, ok I will have the last say and heather can give a bit of input.
P.S. The sooner I get some help the sooner the beast is out of my sight, the happier I will be, please hurry!
Xoxo
Jenni

Linking up with Lee at Freshly Pieced