This is a bit above my ability to explain but I will try my best and I hope it'll be clear and correct enough So when you look at a round form from below there are 2 things to keep in mind. (1) the more towards you it is facing, the more open the circle will be. An (2) the further you go from the point you are watching, the more open the circles will be. Now if you look at diagram (3), first time around, the circles have more or less the same opening, making it seem as if you're looking at a symmetrical object. But the second time around, they get bigger faster at the top than they do at the bottom, making it seem as if the top one is bending away. Going to your drawing, let's first look at red circles, since they are more circular. They are pretty much the same distance from the horizon line but the second one is much more open. It creates the problem from diagram (3). Now the blue circle, It has the exact same issue, it is not that far from the horizon line, you would not be seeing such a big part of it, unless it were bending. Look at the circumferences you drew below, and try to maintain them. Although overall your lines and curves were really nice and clean and honestly big probs to you for noticing that it looks like it bends, it's hard to be that observant with your own work. And these pancakes are really mailable and subjective so I'm not sure how precise one needs to be.