If you were to remove the text, would people still understand the logo?
ive bought a number of tshirts online and of the ten or so, ive been happy with maybe two of them after i get them in the mail.
i would avoid superimposing the image over the shirt and instead display the image ON the shirt so that ppl can get an idea of its placement, how big it is on the shirt etc.
if possible, id show someone wearing the shirt, altho that will add to your initial cost.
"the main goal is to have them buy a tshirt I don't care about looks or design in other senses."
Playing the devils advocate you lost 25-30% market share because your description is in new English.
After that I giving you the highest marks possible because of the integrity of purpose
I know you are going for a very simplified look here, however I don't think it is working for you here. It looks quite unfinished. I would try and really think through the design some more.