Finding a supportive and comfortable bra for a larger chest is a lot like today's job market: without a referral or the internet, you're pretty much screwed. The best bras for DD cups are few and far between. Cup sizes in department stores only go so high, the stock is often picked over, and features that effectively provide support (key word here being "effectively") are surprisingly rare.
My boobs grew in when I was around ten, and they didn't take their time, either. As a preteen, stepping into a lingerie store was my worst nightmare. The pretty lace ones would be right up front, and not one of them would fit without poking or chafing. That's why, for years, I'd default to the boring neutral colored ones in the back. And sometimes, those didn't fit all that well either — they just happened to be the lesser of two evils. Then I learned about the wonderful world of online bra shopping.
No matter the style, the best bras for DD cups offer support without sacrificing comfort. Luckily, the internet has tons of them — and they come in pretty designs and loads of different styles, too, from balconette to wire-free.