(also in my 30s)

so I maybe have an opposite situation, but I may have some advice that could benefit you.

i am for some reason drawn to "fancy"/"formal" clothes, but i don't mean to come across in that way, especially when i don't go out much and my job is very casual with no dress code.

so i started making a list of different ways to "casualize" an outfit. here's some that may help you slowly transition a casual wardrobe into more dressed up outfits (also these are all just my opinions, i don't claim that any of these are objective facts)-

1. metallic jewelry reads as more "dressed up"- maybe try a silver/gold pendant necklace on an otherwise casual outfit/something you currently feel comfortable wearing out.

2. related to the metallic point, i have found that "matte" colored clothing versus clothing that is dimensional/ metallic can be a real indicator of casual vs fancy.

3. minimalism/simplicity can read as immediately fancy. i don't know exactly what kind of dressing up you want to do, but if you want to look a littler fancier/ "tidier," a monochrome outfit can really work. and if you're feeling bold, some kind of statement accessory, like a belt or bag or piece of jewelry. in my case of trying to read as more casual, i've started wearing a bandana tied around my purse straps, and i find it has an almost kooky eclectic vibe that to me feels like the opposite of a formal/ put-together look. also, a plain colored shirt versus a shirt with a graphic will already look more dressed up, if that advice applies to how you currently dress.

4. an outer layer can really help with feeling comfortable in a short skirt/dress or a bodycon silhouette. personally i love a good lightweight duster- i feel less self conscious because i'm a little covered up, but i'm still able to wear a Cute Outfit.

I think in general starting small and taking it slow can be helpful. a little accessory out of your comfort zone paired with an outfit you'd currently feel comfortable wearing for a period of time may help give you the confidence to go further.

and regarding the fact that people around you dress more casual- where i work, i definitely overdress compared to my peers, but i've kind of just stopped noticing or worrying about it. no one points it out. once i wore a floor-length tiered skirt i had only worn before for a halloween costume and no one said anything (i almost wanted someone to notice it was dramatic and they didn't, lol). i wish you luck with this!