My US at the Peri's office said I had a 9mm lining. I went for a lining check at another office (one that specializes in reading US's for transfers). The NP told me my lining was a 6 and we should cancel. I told her we were flying across the country in the morning. She told me we would be wasting our money. My donor ended up stimming a few days longer, but I did get another US the next day, at my clinic. Lining was 9TL. The cycle was a success. I never did go back and tell the NP our results. Another time, the US machine was broken and I had to go to a walk in-clinic. Once again, I was told my lining was 5.9 - 6.0. I did not see how this could be possible, because it had been thicker 4 days before. Also an incorrect reading.
Even though your issue is about patterns, there are many errors by technicians. I definitely think you should go to some place else to get monitored.