Is Stevia suppose to taste bitter?

Cause if it is than, I don't like it one bit! It made my oatmeal taste sour!

i don't think so? I've only eaten the leaves once. wasn't bitter at all.

It is said that stevia can taste bitter if you "use too much". Perhaps you could try a different brand. There are some that state no bitter taste.

That does mean you are using too much.  A little bit of stevia goes a LONG way.