How does the doctor know how my baby is laying or even if he's ok? 33 weeks?

So far everything has been good. My blood pressure is fine, my fundus is measuring right on schedule..ect I'm not worried because I feel him move every day and I know what's normal. I have not had an ultrasound since I was 20 weeks (they didn't tell me how he was laying) and they said they will not do another unless I have complications. They have not externally checked my stomach or pushed down, touched it to feel the baby so how will they know if he's in a bad position? How will they estimate what he weighs? I think he's facing with his back up because I feel two round har spots, one under right ribs and one down diagonal on my left. Never heard of diagonal baby??? I feel mostly rolls and squirms rather than kicks but when I do, I feel them high and low so I don't know if he's in position. They were so great in the beginning and the last couple months they don't do anything except blood pressure, weight, and measure me and tell me everything is fine...