Unusual Period

Emma
So about two weeks ago I was supposed to get my period, but there was only some spotting. I'm on birth control and my cycle hadn't really matched up with the pill packs yet so I expected my period to come this week which is the week of the sugar pills. It's been a few days and it's been very very light. I have taken a few pregnancy tests and they were all negative. I'm just not sure if this could be something I should worry about or if it's no big deal. Thanks in advance