Shopping: try to be glad you’re in a community that shares most of your important values. Colored nail polish is not exactly classy, and most of our traditional communities are conservative when it comes to dress. The reason you feel otherwise is most likely because you grew up in a different environment – and you’re young which makes you naturally more adventurous – so you have a different perspective.
If I’d wear soft pink nail polish with soft grey cat decals/art (nothing ostentatious) would you feel it appropriate for a Bas Melech? Since I’m a grown woman and most likely the women in your former community didn’t wear those, I assume you’d find it unappealing.
And if you want to compare it to tatoos, there are stickers that may even appear real, so no actual issurim involved (perhaps maros Ayin, but for arguments sake let’s assume it’s irrelevant). Would you consider these appropriate for either men or women?
Finally, since our grandmothers going back many generations didn’t wear nail polish, most “chareidi” women didn’t feel it’s right to start this new trend, so they remained without. That’s part of what being traditional entails, although usually change does creep in slowly, hence the soft colors some embrace. Be aware that like everything involving tznios, it may be a slippery slope.
If it makes you feel better, nail polish and the solvents to remove them are generally unhealthy. Avoiding them will add to your schar for the mitzva of protecting your health.