I understand the sentence. Here is how I would say it in a conversation. I am trying to use your example sentence as much as possible. "No. I had a bad experience as a kid. I fell into a river and couldn't get out on my own. Someone had to save me. Even now, I avoid swimming." Have a good day zhangjiliang.

Your answer is clear, but it can be polished to sound more natural and precise for the IELTS exam. Here's a revised version: No, I don't. I had a bad experience as a child. I fell into a river and couldn't get out by myself, but fortunately, someone saved me. Since then, I’ve avoided swimming.

*I was unable to get myself out… *since then I have been afraid…

If you are preparing for IELTS I would strongly recommend taking even just one or two classes with an IELTS specialist teacher such as myself. I have helped thousands of students like yourself to achieve the score they want in the General and Academic exam. Good luck!