She's on the bottom of the pile, while the bigger looking bees are on the top and closer, so they look bigger. If you compare her to some of the other bees down low, she is very distinguishable.
Yes, markings do make them easier to find, especially this time of the year when the population is booming and the bees are 2-3 layers deep.
Yeah, I'm gonna have to learn how to mark queens I think. No kidding though it really does seem like my workers are bigger lately, even when you just see them going in and out.