Learn English – the meaning of “more to come”

Yes:

• In your first year of life you are zero years old;
• In your second year of life you are one year old;
• In your third year of life you are two years old;

And so on. If someone says "I was ten years old", they're referring to a time when they were in their eleventh year of life.

(Note that people rarely say "zero years old"; instead, they usually talk about younger children in smaller units such as weeks or months. People also rarely say things like "in my eleventh year of life"; instead, they say things like "when I was ten years old".)