You could measure the pattern piece (without cutting it out) and see just what it actually measures - patterns usually run large - giving you breathing room. If the top says it is 40" it will probably fit 42-44" bust without any adjustments. If you don't feel you have enough material to make a larger size just measure how long they want you to make the skirt - usually way, way too long. Don't give up yet - would love to see you in this dress!!
I love the fabric!!!