A house, like anything else, is only worth what someone is prepared to pay.
You're under no obligation to accept a low offer but nor are the buyers under any obligation to meet your asking price.
Comments that it is too small, don't like the colour of the paint etc are all just a roundabout way of saying it's too expensive from the buyer's perspective. You are perfectly entitled to think otherwise. Just means you have to wait until you find someone who agrees with your view of it's worth.