Practicing against an engine vs practicing over the board? When I initially started playing chess I used books and board. Later, when I started using chess software, I think my game improved a lot for a time, and I got a rating of 2000 at chess.com

But I am now faced with the following problem: when I recently went to a tournament I was completely blank over the board, and I was feeling that this is a bit different.
I was not able to calculate moves.

The question is: how should I maintain balance between engine practice and over-the-board practice?
Engines do not make tactical or blunt mistakes. However, their calculation range is given by their predefined strength.

People behave differently. In general, their game is rather stable. But they can make big mistakes, or on the contrary, excellent moves, when you don't expect it. 

Also, when playing against people, there is a certain level when psychology comes into account. Stress is generally higher than against an engine, which won't feel any emotions when playing against you.

That's one beautilful part of the game too, emotions are confronted. Good players know how to keep control.