Women can only get pregnant for 6 days out of every cycle. However, the day of ovulation does vary from month to month so that window of time changes each month. For example, in my own charts I see that the ovulation day has ranged from CD13 to CD18! If you have ovulated on CD 21 then yes it’s possible to get pregnant 1 week before your period. If you ovulated much earlier in your cycle and the 6 day window has passed then no, you cannot get pregnant. From the moment the unfertilised egg dissolves to day 1 of your next cycle you cannot get pregnant because there is no egg to fertilise. To determine your chances, you would have had to have known when you ovulated. Unless you were charting your signs then you probably wouldn’t know.
It depends on the length of your cycle. With a short cycle, you may ovulate around then or a couple of days before, so may still be fertile.
It's possible actually but the odds are negligible. It depends on the female reproductive system sometimes it may be unpredictable. If you are not planning to become a parent soon, think about birth control methods. There are so many options, just consult your doctor.