Smackers Press-On Nails don't fit?

I've bought other types like Naliene press-ons and never had a problem because there are many sizes in the box. Smackers only comes with 6 for each set leaving you with little to no room for mistake. My nail beds weren't narrow enough for the nails so the biggest one was still leaving a big gap on my thumb and the smallest one was overlapping my pinky nail. I only attached a few before taking them off. If I took them back to Walmart could I get my money back? Or would it not be worth it?