How many ultrasounds does it take to get to the center of my pregnancy?

Due to the discovery of my two-vessel cord, I am scheduled to have an ultrasound at 26 weeks (i.e.: this Friday), to determine whether baby is growing according to statistical averages. If he's too small, I may be ordered to decrease activity, or even go on bed rest. And of course, I will have to have more ultrasounds, even if he is currently right-sized.

I'm not a huge fan of
ultrasounds. It seems to me to be a procedure that everyone likes, but that
no one has proven safe, or unsafe. And meanwhile I'm supposed to
merrily subject the molecules in baby's little cells to the jiggling caused by high-frequency sound
waves. Of course, only certain books bring up this concern. And that
had to be the books I've read.

Also, we're comparing my baby to averages, not absolutes, and add to that the fact that ultrasound weight measurement
reportedly has a 10% margin of error...

I don't want to be an irresponsible mother. 66% of two-vessel cord
babies are just fine. That's not a strong enough statistic to warrant
forgoing tests, apparently. Even though I really want to not test. Just
in my heart. Don't. Want. To.

And it's only going to get worse. In addition to my cord issue, because of my Advanced Maternal Age
(38) it turns out I am expected to undergo fetal monitoring/non-stress
tests twice a week, from Week 34 forward.

I feel caught up in a medical machine that's based on a lot of
statistics and assumptions, that treats pregnancy like an illness, that
is based entirely around identifying and mitigating risks.

And I feel like a jerk for resisting it.

My OB says there are some tests she's willing to let go of, but these
she strongly recommends. I could say no. But that would be against her
advice.

My doula understands my concerns, and she's not going to tell me to defy my doctor.

To test or not test is one question. The next question will be what to
do if we get a result that raises further concerns and leads to more
procedures. We'll just have to take this one test at a time, I guess.

Are you an AMA mom? Did you undergo lots of monitoring? Please share your story in the comments, below.