I changed the contraceptive and forgot to take some ...

I changed the brand of my contraceptive to a little stronger than the previous one. My gynecologist advised me to start taking the new 4 days after finishing the other. My period lasted 9 days. I forgot to take some pills from the new cartouche and had some bleeding from the leak. What is the risk of getting pregnant in this case?
Expert answer:

You can not know the exact risk, it depends on how many days you forgot, you forgot two days in a row and on what days you forgot (beginning, middle or end of the card). What is known is that if you forget one day there is little risk of becoming pregnant, if you forget two days the risk increases a little more, at the beginning and end of the card the risk tends to be higher as well.