To be honest, with 231 new items for sale, and clothing ranging in size from 10 to 26, you do look very much like a business seller.
If you are buying items to sell, then you should have a business account and a returns policy that complies with the Consumer Rights Act.
Your buyers probably assume they are buying from a business seller, but when they see your 'no returns' policy, they have no option but to open a return stating the item is not as described.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)