I am on 2 x 400mg a day, one morning and one at night. I started on them 2 weeks ago and my ob. said for me to stay on them until I'm 12 weeks which is 3w2d away. That's when the placenta has properly kicked in and taken over. I was put on them because my levels went from 56 to 49 and then down to 29, my ob. said it could be normal and my pregnancy may hold without the extra progesterone but he said he'd rather not risk it and put me on the pessaries. He hasn't done any further monitoring to see what levels are doing now.
I wouldn't think its a good idea for you to go off them just yet, especially if you have had progesterone problems in the past. Can you speak to someone else or maybe if you have enough repeat prescriptions, just continue taking them as normal?