To my eye, the sides look a little straight, from the first picture. Hard to tell without seeing it in person. If that's the case, one trick that might help you is to take a ruler or straight edge and place it along the outside curve of your bowl.
I agree, the curve looks a bit "flat" in one spot.
Another spot to examine might be the curve a little above the base.
The eye, at least mine, can be tricked a bit by shape of the colors (heart, sapwood, and bark).
I find it far easier to evaluate the shape by feel - run the fingers lightly up and down the surface and any discontinuity (flat, slight depression or bulge) might be more obvious. I do this on every piece, both inside and out. Even do this with the eyes closed.
On a shape like this it may help to feel with more of the fingers than just the tips.
I think the rest of the shape is OK except to me it looks a little too "tippy", but others of course may think differently!
But that's hard to tell from a photo. There does appear to be a significant flat on the bottom but a small flared foot might help with both the visual and physical stability (and better show off the curve at the bottom).
I like the bark and don't think it's too thick. (And it still has some green moss in the bark!) It would be nice to see it from different directions, say turned a bit to show a little more of the curvature of the bark.
But the thing about art is everyone has a opinion. (my opinions are worth about what you paid for them!)
JKJ