Thank you for your question. You are right, many customers are finding that this is fitting small.
Here is my recommendation for finding the best size for you:
On the size chart listed above in red, there is a "How to Measure" guide that shows a picture of where to take your measurements. Because this dress is form fitting at the bust and easy fitting at the hip, your bust measurement is the most important measurement to take. When measuring your bust, it is important to go around the fullest part of your bust. You should not rely on your bra/bra band size.
Then, after you are certain what your bust measurement is, compare that measurement to the size grid that is below the picture.
The "Fit Tip Recommendation" on this dress is to "Order one size larger than your bust size". So, if your bust measurement puts you in a 6, you should order an 8. If your bust measurement is between a 6 & 8, I would recommend ordering a 10. It is always easier to alter something that is larger than smaller. You may want to consider ordering 2 sizes larger than your bust measurement if you are a C cup or larger. I say this because the wide/high waistband may sit in an unflattering place along the bust and, by ordering an additional size up, the waistband is more likely to fall at the correct spot because the additional room in the bodice will help accommodate a fuller bust. Then, if necessary, you can have it altered at the sides or shoulder strap so that it fits properly.
If you decide to purchase this dress and you find that alterations are necessary, an Alterations Specialists at any Nordstrom store can mock up the alterations you would like done while you are wearing the dress. They can then tell you with certainty if the alterations are possible and what the cost would be. You should bring the undergarments and shoes you plan to wear with the dress so you can get the best idea of how it will look.
I hope this helps. If you have any other questions, I'd be happy to help here or you can call our Customer Service team at 1-888-282-6060. Let us know how this dress works out for you if you do decide to purchase it; we'd love to see a picture! Have a great day!