I think you are pretty close. The poll results are pretty interesting, especially if you look at the trends:
"Strongly approve" is 15.6%. That's Obama's core support, and it has declined from 71.1% on 5/30.
"Somewhat approve" is 18.2%. It's been declining too.
"Lean approve" is 3.7%. It has declined slightly.
Even "mixed feelings" has increased from 5.4% to 7.4%.
"Strongly disapprove" is 35%. It's the largest category of all, and is only slightly less than the sum of all three "approve" categories.
The people in "strongly approve" either agree with Obama on everything, or would never admit (to themselves) they were wrong about him. They will never change their mind.
But, "somewhat approve", and especially "lean approve" and "mixed feelings" are likely to drift into a disapproval category as Obama continues to prevaricate over the Bergdahl scandal.
If the Benghazi or IRS scandals are ever tied back to this administration, Obama's approval ratings will plummet even further.
My concern: at some point, Obama may decide his legacy can't be saved, and decide he doesn't care about his approval ratings any longer. The danger is he will just do all the things he wouldn't have otherwise considered, and dare Congress to try to stop him.