The phrase 'occupied my thoughts' is correct and can be used in written English.
You can use this phrase to indicate when something has been occupying your attention for a long time, or is on your mind constantly. Example: The upcoming test has occupied my thoughts for days.
"Poetry just occupied my thoughts more".
Reports of the rape and murder of German women in the Gumbinnen region occupied my thoughts during theory lectures.
As for myself, Tallinn was simply an easy and relaxing introduction to the mysterious neighbour that had increasingly occupied my thoughts.
As I walked down the hill and into the woods, I gradually put aside whatever quotidian matters occupied my thoughts, and, by the time I opened the door and entered the studio, I was ready to work.
You've occupied my thoughts, been inspiration behind my words, and have given me hope to believe that, one day, I'll love again -- deeper than I have ever loved before.
"It actually occupies my thoughts a lot more than I thought it would," she says.
With no storm to occupy my thoughts the next day, I tuned the AM radio to something other than weather.
Yet somehow fate has dictated that as we go to bed it is you who are occupying my thoughts.
We are two of more than 200 neighbors under the roof that is our home, and while others intrigue me, Mrs. Powell is the one who most occupies my thoughts.
I am hanging from a cliff, 150 metres above the ground, in the middle of the night, with nothing to occupy my thoughts but pitch-black air, bare rock walls and a dose of vertigo strong enough to cow a harpy eagle.
"I cannot say that I lived as they did because I do not have the weight of loss hanging over me, or the precariousness of the future to occupy my thoughts.
