There is nothing wrong at all with expressing the negativity you describe. You should be able to express your true feelings and not feel the need to bottle them up. While the word negativity could be used to describe it, it's really a positive since you're sharing with the reasoning of being open and honest.
Negativity is only bad in other ways that aren't what you are describing. For example, the negativity on Twitter/Reddit/etc. is what I see as true negativity. The intent to be negative to anger and/or demoralize, and bring others down with you on purpose. That is far from what you are doing and don't associate your "negativity" with that.
There really should be two different words for negativity, but unfortunately there is just one that covers a broad range.