Oh, I'll take a stab at it...
The first four arguments aren't relevant and certainly don't apply to me, so I can set 'em aside.
Many doctors misdiagnose: Some do. The vast majority don't. That's like saying you should never take your car to the mechanic because some of them are underhanded. Taken far enough this argument might boil down to you never leaving your house, let alone your bedroom.
A doctor's prognosis is not necessarily certain: Lots of things aren't one hundred percent necessarily certain. But if the odds are on one side, we generally defer to experts and those who specialize in matters beyond the skills and knowledge of laymen. That's what medical professionals are there for. That there is a slim chance they've misdiagnosed is not compelling enough.
An astoundingly large majority of medical procedures performed in the U.S. are not evidence-based: I'd need to see a lot more documentation behind this. (Out of curiosity: Do you believe vaccines cause autism?)
Some doctors commit malpractice: As ridiculous as some of the arguments above. Some fathers molest their children; some pastors cheat on their wives; some realtors are unscrupulous; some mechanics are shady; ergo, you should never trust a father, real estate agent, man of the cloth, or auto mechanic.
Girls younger than 11 have conceived, given birth, and even breastfed: Which doesn't make it a good or ideal idea (and may in some cases not be medically feasible).