For one of the couples in our local RV club, her not being able to get comfortable with the ride in a 36-foot A meant trading it for a 29-foot C, which they continued to use until she died.
I went through this with mt wife too, she was OK in the cab of a C, but uncomfortable, frightened. most of the time, sitting up higher in the big open space of an A. She also could not sit in the front row of a motorcoach, unless behind the driver. The other side, nothing in front but the window, she couldn't do it. When we got a minivan, it took almost a year for her to get used to sitting that far forward, though no problems when she was driving.
Part of the problem can be fear of open spaces, or fear of falling. Another part is that the motions are different than those in passenger seat of a car.
You can address the latter problem by trying a seat, sofa, lounge, dinette, further back in the coach, more centered in the wheelbase. This doesn't work for everyone, as not seeing forward out the windshield can contribute to motion sickness.
I suggest you just keep trying, see if you can become accustomed. An even better approach might be to syart driving the thing yourself, as the sense of being in control makes a lot of fear/comfort issues go away.
Tom Test
Itasca Spirit 29B