The only way you're going to learn, is to dive in and do some cooks, the more cooks , the more ya learn.
On these forums, you will get a lot of different answers and in the end, ya could be right back where ya started.
So that said, I see two things you're doing that I don't do. First, I would halve that split. That's larger than I burn. And I disagree with Daveomak, you got plenty of fire.
I would also move the fire to one side of the FB . On the other side, I would keep a spit warming, so its ready to burst in flame and soon as I need to move it to the fire.
If you go find a pic of Aaron Franklin's new backyard smoker he's building, or Google up Mill Scale Model 94, and look at where they're placing their their temp gauge. Its on the far end away from the FB, at grate level, near the stack. AF says that's the hottest part of the smoker. And that's cuz he cooks with the door open. Neither one of those smokers has a vent in the door, they use the door itself to control air flow. And they don't use air flow to control temp, they use the size of the split.
You can move high temps from end to end by using the door. Open the door all the way and the air flow will move temps to the stack end. Close the door and just use the damper, and the FB end will heat up.
So point being, its not that important to get your temps even from side to side, its just important to know where your hot spots are at, so you place and move the meat. Its more important to get clean smoke and that comes from good air flow.
I began cooking with an Old Country Brazos one year ago this month, so I'm no long term hand at this. I've got about 10 cooks under my belt. I just bought tuning plates and have done one cook with them, so I'm still learning where to place those.
The problem I found with using the door to control air flow, is my meats were getting bottom burned. The air flow was so strong, it was moving direct radiant heat from the FB over into the cook chamber. I was getting great air flow but meats that were burnt on one side and not done in the middle.
Using the tuning plates and rotating meats, solved that problem on my last cook. But I'm still experimenting on their placement.
But again, this is just my limited experience on a similar smoker and you will have to learn by doing. Some of it can be short cutted, but its still just a matter of doing cooks and not getting discouraged.