Yo-Yo Quilt

The other day, while looking for something else, I found this yo-yo quilt that I had started....15 years ago! I remember it well. We were living in a condo at the time, and starting to look at houses to buy. Anyone who has ever shopped for houses knows how exciting and stressful that can be. So to relieve some of the stress, I started this quilt.

Here is a close-up of the colors that I used.

As you can see, I did have something of a pattern going for a while! But then I must have run out of that fabric, or decided to make it bigger. So other fabrics were added.

I also found these guys in the bag, all ready to be added on, and lots of circles waiting to be yo-yoed. That's probably not a word, is it? Well, I'm in a quandry now. The quilt measures 55 x 49 right now. I've decided that I want to make it bigger, to fit our bed. My questions are this: Do I try to buy more fabric that looks similar to what I've used? Do I continue to attach the yo-yos willy nilly, with no obvious pattern? And finally, am I supposed to add a piece of fabric to make a back for the quilt, or is it proper to leave it without a backing? I've seen them done both ways, and I suppose it's really up to my preference. My thinking was that a fabric backing would make it more sturdy. I'm counting on you quilters out there to lead me by the hand here, and help this poor quilt get finished!