Failed 3 hour but my test numbers are good

Br

I failed my 3 hour glucose test this week and my doctor told me to start checking my blood sugar levels 4 times a day. All of my readings have been below 110 so I don’t understand how I failed the 3 hour test. Anybody else have this happen? Also, I’m pregnant with twins so I don’t know if that has anything to do with it or not.