First of all, I would say that you seem to have a pretty strong handle on your needs and your boundaries. Based on the fact that you are seeking help through therapy to deal with your issues, I would say that you are doing everything you can to move forward with your life in a healthy manner. This is definitely something to be proud of within yourself.
There Might Be Something Deeper
You've obviously spoken to him about this issue and gotten a response that it bothers him and makes him feel like his space is being invaded. Have you asked him why that is? You said that your boyfriend is supportive in many ways. Is he an open communicator? Does he willingly express his feelings about things, or just take a stance and leave it at that?
Often times I have found when someone takes a stance in
anger, as he seems to be doing with this, there is usually an underlying issue that they may not be willing to address. Where is the anger coming from?
For him to be angered at your need in the middle of the night suggests that you might be triggering something else for him. Anger is a pretty strong reaction, and one that would seem -- at first glance -- an inappropriate one. There may be something else going on with him that could justify this response and explain to you why he feels this way. If he responds to you in reaction (in anger and resentment) when bringing this up, it's likely there is another issue beneath it.
He Feels Helpless
A lot of times I've noticed guys have a difficult time contributing in situations where they feel helpless. Even if you tell them how to help you, they often cannot find the ability in themselves to get past their own emotion about how much you are hurting.
What I was told once by a guy is that it can be really difficult for him to watch a woman he loves going through something, and ultimately feel that he can't fix it..
He's Being Selfish
Often times when dealing with someone who is used to putting their own needs first (such as an only child) it can be difficult to get them to unconditionally give their support when their needs aren't being met at that time.
Have you talked about a compromise? I'm just throwing out possibilities about why he might be reacting to you in such a manner, but I would imagine there is a reason. If you can find the reason, then you should be able to find a compromise.
Have you two talked about finding a way that you can get what you need from him and he can still feel that he's retaining his own space? If you cannot even get him to openly talk with you about this and consider your needs as well as his own, you might have a bigger issue than you think.