I can definitely relate. It's hard to find decent sensory-friendly clothing, but I find each time I go shopping I get a little better at knowing where to look. I dress pretty comfortable and plain, I tried being trendy for a few years but since I didn't find clothes comfortable I couldn't stick to it.
I like sports t-shirts made by brands like Nike, Burton, Vans, etc... typically they are made of 100% cotton they are usually loose fitting and come in different varieties. For jeans I like Tommy Hilfiger relaxed straight fit and sometimes I'll even check out Hot Topic. I've managed to find really comfortable and practical skinny jeans and cute shirts from there. I also love the sweaters and hoodies made by a brand called Mikk Athletica. Its usually 100% polyester, but it's super soft and really comfortable with few seams.
If your ever stuck wearing an uncomfortable uniform or formal clothes for work I recommend wearing compression clothes underneath to help prevent the feeling of the clothes hitting your skin.