Plot points aren't the same as act breaks. And act break is basically where the narrative shifts gears between, say, Introduction and Complication. In the case of Star Wars I'd say the first act ends either with Luke's decision to become a Jedi Knight or with the jump to hyperspace.
Act 2 does basically end with Ben's death, so you're right about that. It's the additional and greatest complication, because Luke loses his teacher (or so it seems) and must go on without him.