I am sure you have other important things to worry about? Hair will always grow back and you can have it anyway you want, it is too trivial to fret about.
My hair used to be really thick, and curly. But ever since I got it trimmed, its thin and straight? How do I get my curly hair back?
I assure you getting your hair trimmed did not make the curls go away. It did not make it thin out. What did you put on your hair?
It's definitely not connected with the fact that you trimmed your hair. I personally experienced the similar thing when I moved to another city, and the water quality was different there. So from thick and wavy my hair turned into thin, straight and dry.