i had the same problem after i replaced the stock turbo with a t49. i was only able to get 10 pounds, i ended up ordering a new waste gate from kirbans and solved my problem.
If the waste gate checks out ok then check the solenoid on the dr side valve cover . Also check the wire that goes to the solenoid and se if that’s ok.
If the car only making 10-12 psi normally with a good waste gate, it means that the solenoid is not doing its job.