Am I Not Entitled to my Opinion?

When people tell me, "No one asked for your opinion.", I do get somewhat offended.  I think to my self then you could've said it in a nicer way or not even say anything at all.  "If you nothing nice to say, don't say it at all."  Anyways, we've been expressing our opinions since we were young.  We end up in an endless circle of right and wrong with one another because nothing is always correct.  I wouldn't want to live in a world where one certain thing is correct.  Don't you want your voice to be heard?