I assume by "cycle" you mean how long your period lasts? Normally when we say "cycle" we are referring to the entire menstrual cycle-- from day 1 of your period, all the way through menses, ovulation, the dreaded two week wait, and back to the first day of your next period. If THAT is what you are talking about, it will be very difficult for you to conceive.
HOWEVER. If you're asking if it's normal to have a period that lasts 7 days, yes. Absolutely. The AVERAGE period lasts 6 days, so of course some women will have shorter periods, and some longer. Mine last between 6 and 7 days. I have a wonderful 14 month old daughter.
Good luck to you.
at 6:56 AM on Aug. 2, 2009