I have to agree with pretty much everyone here. Firstly, I find the description in the OP baffling as to how your upper front torso would be exposed while napping with your arms and head resting forward of your waist. However, if you say your attractive bits were somehow exposed attractively, I’ll take your word for it.
Secondly, assuming you were exposed as you said you were, and you believed that others could lustfully look at those exposed bits and yet responded in your heart, “I don’t care,” I’d definitely agree that you should probably confess it… and then find a way to nap more closely to the way you
described (thus making it, as far as the rest of us can tell, nearly impossible for those bits to be exposed

) rather than resting however you actually
did nap.
Thirdly, while I definitely think the cuplability of those who would look lustfully at the exposed torsos of napping teen girls is something that each lustful onlooker must answer for and confess on their own, women, young and old, should never be encouraged to use the other person’s responsibility as a justification for ignoring their own. I can tell you that it is
very hard for many men to look away from exposed beautiful bits on women, and we’d all (well, those of us with well-formed consciences, anyway) be
very greatful if you didn’t belittle our struggle or fail to respect the fact that we’d all
love it if you wonderful, gorgeous women whom we strive to honor as daughters of God rather than to drool over as tempting bits of flesh, would make the effort to keep those tempting bits covered whenever you think of it. I recognize that, as people who’ve probably never really understood or experienced the same type of temptation that we men struggle with, you probably don’t mean anything by it and most likely don’t realize you’re doing it most of the time. But, when you
do realize, like this wonderful OP did, please do respect us enough to remove your pretty, tempting bits from our sight. I’d like to thank the OP for at least recognizing our struggle, even though she didn’t have the energy to take the temptation away from the men around her. That first step is one that I truly wish many more women took.
As for whether you should confess this very moment or tomorrow at midday, I am not qualified to answer… but if you wait till I
am qualified, you’d probably find that you could have gone to confession at a regularly scheduled time many times over while you were waiting for me to tell you what you should do.