The first Bee Suit we bought for 3Reds was huge on her.
We didn't want to spend money on more beesuits that wouldn't fit. So we thought we'd invest in a bee jacket. This time, though, I called the manufacturer (Ultra Breeze), and they were very helpful. The jacket they sent was the right size.
Of course, we still needed to get her a suit. We went to a bee school in Brenham, Texas, knowing there would be vendors present. Mann Lake had some Pro Vent suits, and allowed 3Reds to try them on. It took two tries, but 3Reds now has a beesuit that fits. It's not stylish, but it fits.
So, my advice is to call the manufacturer or go to a bee school where vendors are likely to be. Or both.
Another suggestion might be to ask local beeks who are similar in size if you can try their suits on.