Luuux

Recently I asked myself if it's possible to look smart in a t-shirt. The only answer I have is maybe. Maybe isn't good enough for me lately: I've been spending more time on stage, in front of people and I want to feel smart. I view everything I do in life with a professional outlook. Regardless of how much I enjoy doing something I also have this feeling that it has to be treated like a job: I should be turning up and giving it my all in both effort and appearance. In short I should show that I care.
Some people who have a wardrobe full of t-shirts can usually have a very good "look". My collection of [band] t-shirts is very much me, on a day to day basis, but for some reason I now feel very much awkward wearing them on stage. Maybe I'm just having an identity crisis, I don't know, but what I do know is that I'm finding it very hard to find a decent shirt online.
I mentioned this in my first post on here, but I’m odd shaped – not fat, not thin – just odd shaped. This makes it difficult to buy any clothing anywhere, let alone online. There are only two brands I have ever figured out my size for: Fruit of the Loom and Gildan. Although with the later it’s only been their “Heavy Cotton” range I have made the discovery in. I am a Large and a Medium, respectively. I have never figured out my size for any shirt brand, ever.
What do you guys think? Is it possible to look professional enough in a t-shirt, or must you make the leap to shirts, even in the entertainment industry?