M.D.
The risk is thought to be very small for smokers under 35 years old. You should call the nurses' line at your dr's office to get more info. Here is a related post from Planned Parenthood on the risk of taking hormones (which includes birth control and the progesterone pill that you are taking) and on quitting smoking. https://www.plannedparenthood.org/learn/teens/ask-experts...
You might be interested to know that you faced the same risk for years, whether you knew it or not, when you were smoking with mirena.