The phrase "affected my decision" is correct and usable in written English.
You can use it when discussing how certain factors or information have influenced your choice or conclusion.
Example: "The new evidence presented during the meeting significantly affected my decision to support the proposal."
Alternatives: "influenced my choice" or "shaped my conclusion."
The economy hasn't affected my decision.
"I wanted to stay but the world crisis affected my decision," he said, endearing himself further to Real Madrid fans by humping the Milan badge furiously.
Indeed, upon his signing with Real Madrid, Kaká told reporters in Brazil that he wanted to stay with A.C. Milan but "the world crisis affected my decision," a reference to the global economic downturn and its effect on Milan's pocketbook.
The occurrence of underrepresentation of aboriginal people has not affected my decision to pursue a science degree, but there were times when I would have appreciated a colleague in a similar situation as myself to help smooth out the loneliness and the transition from high school to university.
"I probably realized that too late -- not that it would've affected my decisions in terms of who I dated, but it would've affected my decision to appear on the show".
A biased work environment, conventional family norms and conservative societal dogmas have affected my decisions and actions too.
I can't deny that this affected my decisions when it came to writing the chapter about sex in my book – and it took me twice as long as the other chapters, such was the challenge of hitting the right tone, neither prudish nor graphic.
I never smoked on game day, but it was still in my system so it probably affected my decision-making and my motivation.
Certainly they were necessary and an important part of the business, but the reverse incentive affected my decision-making at the margin.
That didn't affect my decision.
"Brexit did not affect my decision," Son said.
