Hi i am trying to conceive. my period lenth is 35 days. at the 35th day of my cycle i got period but it is lesser than my periods and dark brown. i have severe cramps as well. it is implantation bleeding or period? pregnancy test is negative?

With a history of regular periods, at age "31", unrecogized tubal infections may block your Fallopian tubes, so if successive months your pregnancy tests are negative, first get a sperm count done on your partner, and then ask your GYN physician about a hystero-salpingogram (HSG) to make certain your tubes are open, which is the most common cause of infertility.

It is more likely to be your period. Implantation bleeding is usually just spotting and would have occurred 12-14 days before the date of your period.