Ok, goodie. That means that things aren't half as bad as they could be. Three months for an on-line relationship where you don't seem to talk so often isn't a lot of time to get to know each other.
So your problem isn't with the exhibitionism. It seems to me that you're a bit unclear on where your limits are. That is really annoying for a Master. Anyhoo, since I haven't read more than a tiny fraction of your correspondance and have no idea what you've said of this earlier on the subject, I'll leave it at that.
Here's a suggestion. Maybe less than honorouble, but I think it'll work. Why don't you simply tell him that using blackmail is a major turn-off for you. Why not tell him straight up that what you like is a man that's dominant, assertive but sensitive to your needs. And using blackmail as a leverage you don't think is manly. Even if he doesn't get what you mean, it'll make him listen. No man wants to be less than manly. Yes, that is also blackmail. Blackmail can be good. You have to train your Master just as much as he trains you. That's an intrinsic part of any relationship.
Now here I can see another potential problem. You like writing incredibly detailed journals. Does he actually like that? Has he told you he apreciates it? Remember that he has to read them. If they're for most part rambly, unintresting to read and not to the point, (as most journals tend to be) it may be just a bit too much for him and he has a hard time telling you, (because he off-course wants to make you happy). He does after all have little time to spare.
You can't force a man to open up and become better at communicating. That comes with age and maturity. If he doesn't give you enough feedback and doesn't communicate enough for your tastes, your only option is to move on. Men are not as intelligent as women when it comes to communicating feelings and needs. Women often forget this very basic fact of life. Demanding that he communicate more will probably only make him frustrated and might start making him resent you. It's better to pull stuff out of him. Ask follow up questions on things he asks or says to see if there's any deep thought behind it. My experience is that men often have "smart" instincts and may do things that are a lot more clever and deep than they themselves understand, and they couldn't talk about why they did it even if they want to.
No problem.