one day after a 100mg injection and I'm over 1200ng/dl. I lowered it to 80mg's and will test again soon.
How long after the injection did you do labs? If you're injecting once a week wait until 4th or 5th day following the injection. Some doctors recommend doing labs in the morning because that's when you testosterone is at it's highest level. I go for the average, doing labs in mid-afternoon. When I've had labs done at the end of the week following my injection, my test levels are well below normal.
Many doctor's will err on the safe side. The doctor's prescriptive dosage is often arbitrary. A couple of 1200ng/dl results and your doctor is very likely to lower the dose. IMO, it's better to pay more attention to the other blood work. Rising PSA and hematocrit levels are a couple of areas you'll want to monitor for sure.