Welcome Hollybee!
You have come to the right place. My personal advice is that you always approach him from the front if you want to speak with him about matters that are important. This may not apply at home, when there are no other people or attention-grabbers (computer, TV, etc) present. I don't know about him, but if I am approached from any other direction, I have a tendency to not interrupt my thoughts, hear what the person have to say, even answer their questions, and then continue as nothing happened. This is not good if you are seeking to have a conversation. People around me are considerate enought to wait silently in my field of vision til' I interrupt my thoughts and turn towards them. Please note that this may be one of my personal quirks, and may not apply to your boyfriend.
For a person with Asperger's, communication in general and conversations about important matters in particular, are extremely important to have clearly separated from everything else. We do not distinguish the forest from the trees, nor smalltalk from the important conversations.
I am curious to know if you ever noticed any communication difficulties between the two of you.
I congratulate you on a successfully establishing a relationship. Hope it lasts!