Your listed training rate comes out to 66-76% of max. HR which is fine. 150 is 84% which is right at lactate threshold.
From your description, it sounds like the projected max HR is correct.
Be aware that the various formulas that try to predict max HR are not always accurate. For those who are just starting to exercise, they generally come close but there are those who have unusually high or low maximums.
For those who have always stayed fit, the predictions will be far off as max HR does not fall off with age.
As an example, I will be soon be 52 and my predicted max. ( 220-(current age)is 168 yet I can still hit 189.