I know exactly how you feel, Biro. For a couple of days, I've been feeling the same - worrying about "accidentally" wishing for misfortune. I think it's part of our human nature to bring about problems in this way, especially when we can see our lives improving and negativity disappearing.
So then I decided to
believe that the cosmos / God / my inner self always knows what is best for me and everyone, and only gives me the positive things. It's this trust that I think we've been lacking. I'm trying to believe that no matter what bad thoughts I have, only good things will happen. Like Baerbel says in her book, what you believe is what is.
And my change in attitude is working for me!
But remember that when you "really don't want" something to happen, you tend to bring it about from focussing on it so much. So when an unwanted thought comes up, just know that it can't harm you and let it go.
You're not being stupid ... good luck!
Love Psyche