I’ve found having a cotton t-shirt as a base to actually help when wearing layers, as the cotton wicks away any sweat from my skin and keeps me feeling generally drier and therefor warmer (and I don’t sweat enough to completely soak the shirt, YMMV if you sweat a lot). Also helps if you find wool or other outer layers itchy. You’re right to not wear additional layers of cotton fabric, though.
I’ve found having a cotton t-shirt as a base to actually help when wearing layers, as the cotton wicks away any sweat from my skin and keeps me feeling generally drier and therefor warmer (and I don’t sweat enough to completely soak the shirt, YMMV if you sweat a lot). Also helps if you find wool or other outer layers itchy. You’re right to not wear additional layers of cotton fabric, though.