You seem to have a real dilimma here. To drink or not, to pursue your current path towards a PhD, to begin a career as a substance counselor, and all that makes for some heady thinking. Let's start with the drinking. You've been sober for four years but you seem to question this sobriety since you were forced into it. Let me say that four years sober is four years sober. But sobriety is a funny thing. What you have is physical sobriety - you don't drink. What you're missing is the other (and more important in my opinion) component. And I think that you realize something's missing. I'll put a name on it for you. It's called emotional sobriety.
I'm really impressed by what you've accomplished so far in life. But it's especially significant that you realize something's missing, and it really isn't the drinking, is it? You could always find out if alcohol is the missing link and that's to start drinking again. But from experience let me warn you that that isn't a very good idea. That is, unless you want to throw away everything you've achieved so far.
So if emotional sobriety is the solution to all your problems, and I kinda think it is, then how do you go about getting some of this stuff? I got mine through the program of AA. Walking through the doors of AA after 4 years of not drinking may seem a bit weird, but it really isn't. I've known several people who've joined well after they stopped drinking. But this is only my suggestion based on my experience. Others here may have different ideas and by all means you should listen to everyone. And don't give up on the substance abuse counseling idea. With what you've undergone and what you've accomplished, you'll make a great counselor. You just need to polish up that emotional stuff.