Would it mess a relationship up to do bf/gf stuff (Hold hands, kiss/hug, intimacy) if the relationship isn't official?
It could. In general, those kinds of expressions are reserved particularly for committed relationships. When you haven't committed to someone "officially," and thereby not committing, you have also not set proper expectations, then it's very easy (and often case) for each person to have different expectations of boundaries and what to expect or not expect from the relationship. Our words matter and say a lot, but our actions are louder and say everything. When one person is expecting more or less than the other is, conflict is the result and you run the risk of ruining the friendship/relationship and losing that person. If you feel that you're ready to give those kinds of expressions, then it's time to discuss committing to that person. But if BOTH of you are not ready, then it's best to pump your brakes until you are ready to commit (on some level) to each other. That means both of you should be ready for a relationship, not one of you is ready and the other kinda, but feels forced in order to please the other—no, that usually leads to problems later. And if both of you are not ready, that's ok. You can really learn about someone and enjoy them during your friendship stage.