My period is usually 6-7 days long. but this one and last one 8 days and heavy then after on day 9 just lot of discharge?

Possible infection: If discharge is unusual for you and it is other than clear mucus u should see your gynecologist.

Normal variation: It is often disconcerting when your period goes along in the same pattern month after month, & then, for no apparent reason, something changes. But we are biologic organisms, & things are constantly changing. A change in flow is often due to changes in hormone balance or even a period where ovulation hasn't preceded it. Will likely return to usual pattern soon. If changes persist, see your doctor.