Going for a more older, sophisticated look.?
I think that's great! And a big thumbs-up to wearing high heels and dark wash flare leg jeans and nice shirts. It's amazing how well you can dress up with a blouse, stilettos and a pair of long floor-grazing flare leg jeans. Very chic and feminine and very flattering and sophisticated! It's a far cry from the totally over-worn skinny jeans, leggings, tees and converse look which is so common and unimaginitave that it's just plain boring.
Other items for sophistication are pant suits and skirt suits, high heels, blazers and dressy separates. Focus on looks such as blouses, blazers, wide leg or flare leg long dress pants and knee-length skirts like pencil skirts. Other skirts to consider are mid thigh length circle or swing skirts. They are loose and flowy and a little flirty. Just be careful with these skirts on windy days and make sure to wear full coverage panties and/or pantyhose. And speaking of pantyhose, be sure to have some in sheer black, nude sheer and light beige. Pantyhose are important for a well-rounded and professional look for formal events and church and for job interviews/office jobs. At 19, you are at the age where you are expected to dress up more adult and less teeny-bopper so it sounds like you are ready for that transition. I'm not saying you should never wear fun casual clothing like leggings or your fave pair of bootcut yoga pants. There is a time and place for those as well. But you are probably either working now or will soon be looking for work so now is a good time to start dressing up.
I suggest to stay away from the discount stores like Ross, Marshalls and TJ Maxx because their clothing selection is very inconsistent and limited. Also, the teen stores like Rue 21, F21, Urban Outfitters, Hollister, A&F, Charlotte Rousse, Papaya and the like are only going to offer casual trendy teen clothing that is anything but professional and sophisticated not to mention their clothes are cheaply made. Unless you are shopping for bandage dresses, leggings or jeggings, these stores are typical and unoriginal.
For good clothing stores, consider Express, Ann Taylor Loft, Zara, Dillards, JCPenney, New YorkCompany, White House/Black Market, Gap and even Victoria's Secret. I've found great clothes at all these stores for my professional retail management job which requires dressy clothes like skirts, dress pants, high heels and pantyhose.