I'm not going to suggest a book because I doubt that is really the issue. I suggest finding a tutor for a few hours and see if things then make more sense. A tutor could just be a fellow student who seems to get it.
QM should not be left to self-study in my opinion. I recommend taking a course at a local college instead. I say that only based on my own experience taking QM in college and the fact that you then have an expert to ask questions of.
I found the problem in my copy of H&R and it's completely different from the OP statement. I shall type it out. This is from the 1978 version of combines parts 1&2
In fig. 27-4 consider two neighboring lines of force leaving the upper charge at small angles with a straight line connecting the...
Then the error is in H&R which I'm skeptical of. That figure is a cut through one plane and it looks the same in any plane around that axis. If you pick any two lines of the top charge in that figure there is some distance where the angle is half between the tangents.
Doesn't it say tangents between any two lines? Question #7 in chapter 27 of my copy of H&R asks why the lines of forces from fig. 27-4 when extended backwards, appear to radiate uniformly from the center of the figure.
True if this were a problem in Jackson but this is a HR problem which implies at far enough distance it looks just like a single charge of ##2q## and the lines are spread out evenly. Twice the lines over the sphere implies half the angle between any two lines over the single charge case. I would...
Then assuming there are N lines around a single charge in the close case they are evenly spread around the sphere and in the far case N lines are spread evenly around a half sphere. In any plane cut through the sphere the angles between any two line's tangents should be half in the far case.