That is a Custom Pit made in Georgia. Read through the following thread; it starts out like yours (frustrating for a new pit I know) but I think folks with these pits have identified solutions, if memory serves it means increasing the size of the exhaust to get proper low, but yors looks like it might already have a larger exhaust - how big is it?
EDIT: Sorry about that, fixed the link to boiler93's thread.
Weber 26.75 OTG w/CI grates & SJ/WSM Mini
Home built 24"x72" reverse flow stick burner trailer with 18"x40" grill w/CI grates and upright SS gas oven/smoker.
Home built 48" fire pit with a 30"x30" Santa Maria style ranch grill.
Home built lump charcoal retort, iGrill & a bunch of other cooking toys.