1. They don't understand the cup size equivalents.
2. They haven't been properly measured.
Let me address the measurements first. If your bra fitter did not take three measurements, she has been trained to fit you into certain brands of bras. Many companies do not offer cup sizes larger than a DD so they use two measurements and add 4 or 5 inches to make up the difference. Another problem with fitting is when moms measure themselves, the assume the size under the bust is equal to the band size.
Here is the scoop on bra fittings:
1) Make sure you get three measurements.
2) Understand whether you are buying a full figure bra or a standard bra.
Not all bra companies use standard equivalents. Most brands like Bravado Nursing Bras, QT Intimates, La Leche League Intimates and Amamante Nursingwear are as follows: 6" difference between under the bust and the fullest part of the bust = DD, 7" = DDD/F, etc. That is where the confusion comes in so let me make it clear. A DD cup = E for full figure bras, DDD = F, but if you are used to buying a standard bra that comes in cup sizes B-DD and no higher, there will be about a half cup size increase between the DD in a standard style and a DD/E in a full figure style. To clarify, full figure styles start at D cup size; they do not make the B or C cup. That's how you know if a DD will equal an E.
Some manufacturers like Bravado Designs Nursing Bras advocate a 2 measurement method, but do offer larger sizes. You should still use the 3 measurement method to get your Bravado Bra size, as their size charts still correspond since they use a multi-cup system. For example, they offer a 36FG which fits both and F and a G cup. Some of their styles fit an even wider range of cup sizes. For example, the Bravado BodySilk Nursing Bra comes in 4 sizes, but also Consider Amamante Caress & Contour Nursing Bra which has two sizes making it very versatile and affordable option for the new mom whose shape is constantly changing in the early weeks of breastfeeding.
To make things even easier, go to our fitting room for full measuring instructions and a sizing chart.
Shop by nursing bra size here.
When you order bras online, make sure to order at least two different brands in the size you are measuring. You would not take just one swimsuit into a dressing room and expect it to fit. The more nursing bra styles you try, the better the fit. You may also want to order more than one cup or band size if your are measuring an in-between size. When you receive your bra, hook it in front of you and then turn it around to make sure you know which hooks you are using for the band size. Then turn it around to put the straps on. Then either lift the bust into the cups or lean into them to ensure that all of the busts are in the cups before determining if it is the right size. DD and DDD are by no means the largest cup sizes as we offer nursing bras that come in cup sizes G, H, I, J, K, L and M!