Can you eat supplements? Im not sure if most will intervene with your vegan diet.
You will have trouble finding brands, specially the ones that are not overly expensive. When I had a 35 chest and I found it really hard to get fitted clothes. I would try AX, their XS shirts/solid tees might fit, and they have free returns. As far as tops go, it was almost all I used to wear. Quality is quite decent and fit was great just wait for the sales.
Jeans you can try dior homme 17.5cm their thigh measurements for size below 30 are tiny.