Do you know about parakeets?

WOW! That is unbelievable you have had her that long. I had one once but it only lived about 18 months. I was told they only had a life span here in my country of 2-3 years. That should be exciting to see one lay an egg. You should encourage het to sit on the egg, put a box with hay or straw in there for her to sit on the egg. If she does not sit on it or if you remove the egg she will continue to lay eggs.