& three years is recent.
It is a loss you will process over the course of your life, it won't always be raw and so distressing. Like Crypts said, there are no rules, no timeline, it is a part of life.
When you see your aunt with her daughter it may be you are grieving the kind of relationship you did not have, or have a chance to have; or that you are missing something you once did have with your mother...or something else....((((hug)))))