Tiki: young male plakats can have a false eggspot to "fool" the adults into thinking they are female and to not be eaten/attacked.
Welcome to the forum.. very pretty little one you have.
Since you got it at Petco, the fins and body shape and lack of beard is telling me it's a female.. they tend not to sell too many males unless they are large enough to have their long tails and past prime breeding age. Females they ship out as soon as they can.. around an inch. Most likely she will turn into a darker blue, tail type looks very close to a veiltail.
She seems to have a touch of ammonia burns and possibly fin rot- I would do a few extra water changes this week for her- every other day 50% for the next week to help clear those up.
She is small, 2-3 meals is a must per day for her, most likely you will either have to use mini pellets or cut up the common sized ones.. but she's going to need a good amount of nutrition.
Keep us posted on her progress in whether or not she is a female/male, and as always, more pics!