Early on I thought my broad shoulders would be a problem with womenswear, but I've found it's seldom an issue for me. As with any clothing shopper, you want to learn to buy the things that emphasize your assets and de-emphasize your figure issues. There are no solid standards in sizing for women's clothing and actual sizes vary widely. The only way to be sure is to try things on. Of course, with online shopping that can be costly and time consuming, but it's possible. Try shopping from the few online sellers that offer free return postage. I did an extensive search for these awhile back and now only shop from this list. They all offer free returns:
Asos, Foot Locker, Gap, Old Navy, Banana Republic, Macy's, Zappo's
I've done well so far ordering from Macy's and Zappo's. Zappo's has a great search system that ferrets down things. They used to be just a shoe dealer, but now have a full line of clothes as well. Asos is well known for their tall sizes, BTW. Don't be too put off by the high prices of many items at these stores. They all off sale sections and usually run 20% off or free shipping code deals that bring down the prices. Shop carefully and you'll do fine.