Glad to hear you're enjoying it! You can actually find quite a few testimonials / stories about using the builds in games on here by now (including a few on just the last page of the thread)... it's just sort of scattered all over the place. But it's always nice to see more =)
My advice here would be to reverse your thinking a bit. Instead of thinking "how can I force my enemy to move," think "how can Team PCs capitalize on an enemy standing still?" Think of it less like a pure damage bonus at this point and more like Sentinel. Encouraging the enemy to stay still is the point, the threat of damage is the means by which you accomplish it. Positioning is king in tactical groups, and you deny the enemy's ability to position (or at the very least, tax them for it).
Your allies now can line up cover easily, lay down hazards, control who's in reach of the enemy easily, and more. Hazards can be as simple and accessible as an Unseen Servant or Familiar starting an oil flask fire, a caster using Create Bonfire, etc. Or they can be much deadlier abilities. Even just the situation of "the enemy stops moving and starts attacking the Tank build Fighter instead of, say, that squishy caster" is a nice thing for you.
There's stuff that'll force an enemy to move too, of course. You'll synergize with teammates who use things like Dissonant Whispers or Command. But again, the Booming Blade OAs are there for control/tanking first. If they're encouraging an enemy to stay still, then it's doing its job.
But really, you don't have to force them. Just take advantage of them not moving, and you'll either benefit from that, or they'll decide that the damage they take isn't as bad as whatever the consequences of not moving are (and then you'll get your procs).