At your weight, it shouldn't be too hard to find stuff that fits. I'm about 20 pounds heavier, and I find some good stuff.
I have team clothing from Pactimo and Biemme. Biemme fits best, just a tad larger than Pactimo's, certainly more stretchy. These were gotten through team orders, but you could just check out their websites to find a dealer.
I also have purchased online some Castelli and Hincapie. My Hincapie shorts fit the loosest of all four brands. I have one Hincapie jersey and it is loose, too loose in fact--I don't like wearing it.
Castelli shorts fit the tightest of the four, but the jersey I own is fine. The cuts on the Castelli are perfect for riding (not necessarily walking upright). Castelli has a complete range of cycling clothing: arm, knee & leg warmers, wind vests, jackets, gloves, caps, etc...
I got both Hincapie & Castelli through
Bonktown. They sell one item at a time, just watch for the deals. Other clothing I have gotten online I use Google Shopping to find the best deals.
I tend to favor the "second skin" fit, otherwise known as "race cut" or "european cut". I don't like the look of myself in them (say, "sausage casing"), but then, once I'm out there, hammering away, how I look isn't high on my priorities.