Hello, and I hope I can help you today.
You are correct in the fact that after missing your birth control pill for four days you do need to start over with another pack. However, you are supposed to start that pack as soon as your next "period" begins, not ends, even if it came at the wrong time. So you really should have started a new pack a while ago, and you should have used a backup method to prevent
pregnancy in the meantime.
It sounds like it has been about three weeks in total since you took your last active birth control pill. So if your menstrual cycle off the pill is regular, you should be expecting a normal menstrual cycle in about a week. If you decide to wait until your next period starts, you should start the pill in the same way you did when you first started taking it in general- either starting on the first day of your period or the Sunday after your period begins (if you get your period on Sunday you should start that day). Ideally you should be bleeding when you start the pack, this will ensure that you get your menstrual period during the pill free week and also protect you most effectively against pregnancy.
What will get you back on effective birth control the fastest is to just start taking the new pack immediately and use a backup method of birth control during this first pack. You may not menstruate at the correct time this month, but it will get back to normal once you have gotten back to taking the pill every day and not missing any.
If you do not get your period at the end of the new pack, I recommend performing a pregnancy test just in case if you had unprotected sex in the time period between your last menstrual cycle and now.
So in summary, you will be protected against pregnancy fastest if you start your new pack right away. In the future, please remember if you miss more than two days of your birth control pills, the best thing to do is to immediately start a new pack of pills and throw out the old one. Your menstrual cycle should come at the end of the pack that you took correctly and completely.
I hope that I was able to adequately answer your question today, and that my advice was helpful.
Best wishes,
Dr. Brown