First of all a Independent clause consists of both a subject and a verb and can stand on it own and make a complete sentence. A subordinate clause is a dependent clause which too consists of a verb and a subject but does not stand on its own and isn't a complete sentence.
In this case the Independent clause is "She feels a sense of joy and fulfillment". The subject is "She" and the verb is "feels" and this can be a complete sentence.
"When Jamie does volunteer work" is the subordinate clause. The subject is "Jamie" and the verb is "does". Also, this is not a complete sentence.
So one independent clause and one subordinate clause.