Aymee, I've been looking at these pics all night! Did you use the small size of the pattern? If yes, then the pattern is too big for her, and you can resize it before you try again.
Measure her girth, just behind her front legs. (You can add a tad so it's not super tight: however you would like it to fit her). Then pin pattern pieces #4 and #1 together at the seam and measure the pattern where it goes around her middle. Subtract 1 inch from that number (for two 1/2 inch seam allowances) and 3-5 inches for the velcro to overlap and then compare it to KS's measurement. The pattern small size is made to fit a dog with a 11-13 inch girth, from her pics it looks to be 1-2 inches too big.
Take her measurement from where her neck meets her shoulders down to about 2 inches before her tail starts. (I believe the skirt on this dress is shorter than most, most go to the end of the butt). Divide that number in half. Then measure the bodice from the neckline to the girth, and subtract 1 inch for the seam allowances. Compare and note the difference.
Then pin the pattern to decrease by that amount. I've done this pattern to decrease an inch.
IMG_0753-1.JPG Pin these two pieces (1&4) together and measure, allowing 1 inch for the 2 seam allowances.
IMG_0754.JPG Separate the two pieces and fold them in half, matching the neck parts together. Measure 1/2 inch for the fold (to decrease by 1 inch), pin the fold lengthwise. You may want to make piece #1 a bit bigger than measured to allow for sewing. If that piece fits her chest, you can leave it and just make the decrease on #4 bigger. Be sure it fits around her neck before you cut the material. Make the decrease on the band (#8) also. The width of the band can be left alone or decreased, either way.
IMG_0757.JPG Lay the folds to one side, then make another fold at the legholes, to decrease the length of the bodice. This may make the holes oddshaped, just cut the material as rounded as you can (to match the look of the original pattern as best as you can.
Then pin this to the material, and follow the pattern's directions.
Hope this helps...