Ob-Gyn questions? Ask a gynecologist online.
Progesterone is used to support an early developing pregnancy until the placenta can take over Progesterone levels are very high in early pregnancy. Taking progesterone cannot cause a period when you are already pregnant. It also cannot effectively treat bleeding episodes in early pregnancy. If you have had an ultrasound and there is a heart beat, its not likely doing any good or any harm either.
If your Dr recommends it till 12 weeks, take it until then and then stop. What tests are you referring to?
You will need to stay on it only until the end of the first trimester then 13 weeks.
You should only take it to 13 weeks It does not need to be tapered. It can just be stopped. First screening (Nt scan and bloodworik) is done between 11-13 weeks.