Is being 3 dryas late a bad thing.. b/c last month had 31 days.. and I came on the 21st last month.. and this month has 30 days.. and I assumed I was going to come on da 21st again.. but today is the 24th.. is this bad?

Your period won't come on the same date every month.

How old are you?

Being 3 days late is nothing to worry about. It would actually be rare for you to start the same day every month.

Your period won't come on the same date every month.

How old are you?

1992 in S/N... my guess 17.

Your cycle runs in days, hense the term 'three days late', there are never equal days in a month. So if your cycle is 28 days, that is four weeks and will not fall and begin on the same actual 'date' every month.