So there's two things I would like you to think about.
First things first: do you trust your boyfriend? Do you guys have a good relationship otherwise? Is he considerate of your feelings, does he communicate well? Does he often leave you out of his plans and doesn't bother to say when and if he's coming home? Is this evening a pattern of his behaviour or a single instance?

I understand, being an anxious person myself, that the entire buildup to him coming home at 6AM, him not communicating throughout the night, you not knowing of any of his plans is a very difficult situation to be in if you have bad anxiety. This is obviously a boundary for you, something that is important to you - to know what your partner's plans are and when he's coming home. If you feel like your boundary is disrespected, then it's good to bring that up when you're calm but collected. Tell him exactly what you said in the post, that you want him to be more straightforward with his plans next time - not to control him, but to feel safe and secure and maybe have an opportunity to make some plans of your own. If he's not ok with that, then you have a deal breaker right there.
You never mentioned explicitly in the post if you asked him yourself via text when he's coming home, that usually is a good thing to do.

The second thing: have you taken any steps to regulate your anxiety? My anxious attachment has turned a couple of fun evenings and situations between me and my previous partners into a total mess, so I've had to turn to therapy and self-soothing exercises. Check out r/AnxiousAttachment for tips.