Don't feel along Katie - you have support from like minded people here

- especially me!!
You must not take the way he works with you personally even tho it may feel like it is aimed at you. Sounds as if he is set in own ways. Perhaps his previous PA/secretary was not much help to him and he does not realise what you could actually do to help him.
I think that the only way to improve how you work with your bossie is to sit down with him and explain calmly - not in a way that may sound as if you are moaning but one that is sympathetic to his situation - that you are here to help him as much as you can, in order to make his office life run smoothly - certainly more smoother than it is now, so he does not miss deadlines, have double bookings etc etc.
You could say that having worked with him for XXX months now, you can see areas where certain aspects can be improved and have a brief list to discuss with him. I did start having 15 mins first thing in the morning with my bossie and this did help. Storing things up is too much for him but quick bursts is enough to keep his attention. This has tailed off for a couple of weeks as he has been away but will start again soon.
Obviously you will have to book time in his diary and only you will know when a good time is likely to be. Walk in with a cup of coffee or something and sit and explain how you can help him. You need to sound firm but understanding of his 'pressures'.
Can you code emails he needs to read or action with a red flag, for example, so all he has to do is skim his in-box and pick out such messages. Others can be read as and when.
Can you take full control over his diary and not let him/others book things in?
He may be overwhelmed with work he has to do but (aren't they all!!) but there comes a point when he has to just sit and calmly read emails/write a document/make calls and not say he has not received it, for example, and not run around like a headless chicken but getting nothing done.
I often joke to mine, I am going to lock him in his office until he has completed XXX - he smiles and gets the message but 6 times out of 10 will get side tracked but at least we both know I have mentioned it.
Communication is so important as you know, keep trying to talk to him and raise urgent/important matters, try to be one step ahead. You can only do your best.
Let us know how things develop? Good luck.