Why Am I Having Lower Blood Flow During Periods?

iam 27yearold with height 5 feet 4" and weight 57kg.Till last year my periods will start regularly in average of 29 days, but recently in some moths evevnthough periods will start in 29days after atrace of bleeding i wont have bleeding on the first day.it may start only in next day and i feel quantity of blood flow is also less.Is this any problem.Iam trying to conceive.Whether this will affect my pregnancy plan?