Seeking a "how to" from ladies who have successfully come off P4, please

I know, another P4 question, I apologize and thank you in advance if anyone can offer some advice.

I'm 11w1d today and just back from the OB. Had first abdominal scan, very cool but the machine was new and she didn't know how to get the machine to work so we could "hear" the heart (grrrr) Bummed me out a bit (all these weeks getting to hear it has been reassuring) though I saw it beating away on screen.

While my OB has been supportive about P4, she is kind of "rolling her eyes" at me NOT wanting to just stop P4 cold turkey at week 12. I told her today (sort of firmly) that me stopping cold turkey isn't going to happen and I would feel more confident weaning myself off starting at week 12. While she supported me in doing that, she offered no advice about how to do it. Here are my questions

1. I am taking Endometrin 100 mg 3x a day. Next Monday, when I start to taper off, would I cut out the one I take midday, and just go down to 200 mg a day? (you start tapering off at the start of 12 weeks or the end?)

2. At what point do I ask for a P4 test and how do I know if my level is "okay" to taper off the following week? Should I expect a drop, because I am on endometrin and it doesn't show in the blood.

3. How many weeks does it take to go from 300 to 0? Is it every week you lose 100mg? Or do you do 150 on one week before going down to 100, then 50, then 0?

3. Will I need to get a weekly P4 test once I am completely off the P4? (She told me she never tests P4 beyond week 12 because the placenta takes over and I had to go there...and tell her "well I have heard of the placenta NOT taking over at that time and women experience a drastic drop in P4, I would hate to have miscarriage #5")

I got the feeling today that she is a little fed up with me worrying so much but that's TOO BAD! If there is anything I forgot to add, or any other advice you have about tapering off/levels/ things to watch out for, I would appreciate it. Thanks so much!

Teresa