Need suggestions on how to make a square top...rectangle and bigger

[coffeebreak]

Still struggling with this "Lovely" charm quilt! It is good that I love these particular charms and colors or I would have trashed it long ago! But.. here it the top as I have it finished. I do like it. It is 45 wide by 45 long. I used 4 packs of charms but only liked these charms. The others didn't match as they were totally different prints. Anyway...I worked and worked and finally got this design that I like. But.. now for the problem. It is 45x45. I need it to be at least 65x85 as it will be a blanket on MY bed...yep...first time a quilt for ME!. I purchased these fabrics to match the colors in the charms/prints and I have more of the beige to go with these. Since it is square... how do I make it rectangle..and make it look right? I know just add borders to make it wider, but...to make it longer...means to add borders only to the top and bottom and NOT the sides. I figure make it wider as I need, then add to the top and bottom from there...but...it will look "off" as more borders on top and bottom than sides. I've been tossing this around for awhile, but haven't come up with anything that would look right. Any suggestions?