Purpose often appears after usefulness begins.

Purpose is usually described as something you find first and then act on, which leaves people waiting for clarity that does not arrive. In practice it tends to run the other way. You start being useful somewhere, the usefulness produces feedback and attachment, and a sense of purpose forms around what you are already doing.

Stop trying to identify your purpose in the abstract and pick something that needs doing near you. Do it properly for a few months. Meaning tends to arrive on the far side of that, not before it.