Gauge can be such a bear (for me at least).:ick: Are you getting the gauge called for to get the 48"? Sometimes I get gauge on my swatch, but when I actually start knitting my gauge is not what I wanted, and I have to start over. Is the 34" you're getting for the width of the piece going to be doubled, as in is this only the back or front, or if done in one piece is this what only half of it measures? Seems obvious, but I don't know your experience level, and you may not have thought of that. If it was only half, you would be getting pretty huge though. :think:
If you were getting gauge for the body and the math works out that it is going to be the right size but the bands seem too small you could make the bands over the full 145, even on the 10.5 if you have too. I've always heard the bottom of a sweater should pull in a little, but if you have a generous hip measurement it may be better for it to be more full. You might try the full 145 and a 9 for the ribbing, if the gauge is going to be right for the body. Also, I just have to say, that sometimes things seem wrong at some point but if you started with the right gauge on your swatch, sometimes everything works out if you just keep going.