If you can find (and afford?) occupational therapy, look into it. Even for an adult, it is very meaningful to go to OT. I'm 23 and they were saying that there's still hope to actually change some of my nervous system to make me less hypersensitive.

For shoes - I wear vibram five fingers. They're worth trying on to see if they're the type of shoe you'd like. Your feet do have to adjust to them, but the basic idea of whether they'd be comfortable you can probably figure out in a store. They're the only shoes that feel comfortable to me, they also help with my propioception problems.

For clothing - it helps some if you can identify what known problems are. For example, I can't wear stiff clothing. That makes it easier to skip over what known problems are and others can help you look for clothing that's nicer for fancier occasions. Tags are usually cut-out-able, so check that before you buy anything. The other option to deal with tags is to layer clothing more - I wear compression shirts underneath a lot of what I wear. It gives me some deep pressure input and makes what I can wear a wider set of stuff. Second hand shops are really useful when you have sensory issues with clothing.