Normal dosage is 100-200mg per week. You're at 167mg per week.
What isn't normal is to inject only once every three weeks. Typically, you don't want to go any longer than one injection every 7 days. Many guys prefer to inject twice a week (every 3.5 days). Many like every 5 days.
Injecting once every three weeks is going to put you on a HUGE roller coaster and you are going to have MAJOR estradiol problems. I hope he put you on an aromatase inhibitor too.
I would encourage you to do a lot of reading of old posts and the Stickies on the testosterone replacement therapy (TRT) forum. You can learn a lot from the experiences everyone else has had. Then come back and keep asking more questions after you have had a chance to read up on TRT.