Sounds to me like you're right. Should I wear these shoes with this dress? Yes, you should -- they match perfectly. People often just answer with "yes" or "no" to questions in general. Just "yes" or "no" is enough. However, adding "...you should." is not wrong. If someone habitually answered EVERY question in full form, that might be weird. Sara: Do you like chocolate? Bill: Yes, I do. Sara: Should we get the chocolate cheesecake then? Bill: Yes, we should. Sara: Are you paying? Did you bring your wallet? Bill: Yes, I did. See? It gets a little weird :-) Sometimes people give full answers, just not all the time. That's just my two cents.

''Yes, you should.'' sounds like the only proper answer. Who on earth told you it was wrong? PS. Use ''I need help'' or ''I need some help'' - help is uncountable, so ''a help'' doesn't make sense.

"yes, you should" is a correct and often-heard answer to "should I...?" question here in the US. So whoever told you that was wrong. Best wishes!　：）））