Gestational diabetes at 29 weeks

I keep seeing that the 1 hr glucose test should be done between 24 and 28 weeks. My doctors waited until I was just 2 days shy of 29 weeks and I failed with a 171. Then I had to wait to get the second 3 hour one done. Now I’m going to be almost 30 weeks by the time I get these results. If they come back that I have gestational diabetes then I feel upset that they waited so long to test me when I could have gotten this under control weeks ago. Other people I know were tested around 25 weeks. Is this still normal to be past 28 weeks. I feel really upset with my doctor about this and just want to hear about other people’s experiences.