I am confused and frustrated.

I was scheduled for my last prenatal checkup with Dr Mochwari at Meadowlands Zone 9, who was my doctor from the very beginning of my pregnancy. I arrived there on the 12th of August for my sonar and checkup and got a different doctor by the name of Dr Ntlanhla. According to Dr Mochwari I would be 33 weeks on the day but on my arrival Dr Ntlanhla said I was 35 weeks with absolutely no explanation. My sonar was incomplete, it literally took 5 to 8 minutes and all he said was, "I can only see the baby's back so there's nothing I can do". With Dr Mochwari, my experience was always different - if he couldn't see much on the sonar then he would do something about it so he too is satisfied. With Dr Ntlanhla - complete opposite. I had to remind him I need my prenatal meds as well since he didn't seem prepared to do his job on the day. It was a complete waste of R500 and he couldn't wait to tell me to pay before I leave. I then went to a clinic where I was planning to give birth and I was informed that there's no such thing as a final prenatal checkup, I was supposed to be checked weekly until birth. Now I'm confused, not sure if I'm 40 weeks or 38 weeks now, I have no information about how my baby is doing whatsoever and my meds are finished.