I'm often mistaken for younger than my age (28 this past April but still get suspiciously carded when I try to buy alcohol, even by bartenders who don't card my 26 year old sister) too, but luckily it doesn't matter much in my daily life. For some reason, probably because I can't afford to shop at Anthropologie (lol), I've never felt hugely drawn to wearing novelty prints (unlike traditional prints like polka dots, stripes, floral, & plaid, which are all well represented in my closet), but I do have a little brooch collection that is kind of my novelty print substitute! I tried wearing them after reading about Madeline Albright's brooches in her memoir Madame Secretary and found I really enjoyed it. They add some extra whimsy & personality to my outfits & are easy to buy secondhand or from independent craftsmen. Maybe that could work for you too?
I love novelty prints on other people: they make me smile. Could you try adding one in your casual wear, where your age isn't as important? I know you have a small closet though, so would you get tired of wearing the same print frequently (vs a solid)? I love the bags you've shown & since you wear mainly solids, it'd be easy to coordinate.