Proud versus Happy

I have an issue with the word 'proud'. As a matter of fact I stopped using it completely quite few years ago now, and instead, I've been using the word 'happy'.
Usually when we or someone important to us achieves something we say: " I'm proud of myself", or "I'm proud of you", or "you should be proud of..."

So does it mean that if we don't perform to our highest standard (for whatever reasons) it's time to be ashamed?!... As shame is the opposite of pride.