I think you're reading too much into this one test. Yes it claims its from a real IQ test but is there a way to verify that statement. Gut feeling. Seriously doubt it. Plus IQ tests test both verbal and performance. You could be higher than average in either one.
You are definitely not worthless, a waste of space. You express your thoughts very well. I say that IQ test is waste of time. Its terrible this one test result is making you feel so low about yourself. My suggestion you should think how valid this test is. Personally I say its crap.