Pinkpum looks like drop shipped Chinese clothing. Every listing I see on Amazon, eBay, etc. that have brand Pinkpum underwear, but the underwear is labeled as a brand called Glestore in the images (like this). All of the stuff on Amazon with Pinkpum and Glestore branding all use the same images as drop shipped Chinese clothing. It's likely why you had to size up. The most common thing you have to do for Chinese knockoff clothing is size up.