"I did not plan this."
Translation:Nie planowałam tego.
The infinitive is planować. I planned is either planowałem (masculine) or planowałam (feminine). In this aspect of course.
Not wrong, but it's like... "Woah, this I did not plan!" You look at something, and you say that it absolutely wasn't your plan, that you didn't expect such a result. And "Nie planowałem tego" is a completely neutral sentence.