I've been on the pill for about half a year now and I skipped my last three periods and then I took the sugar pills to get my period two weeks ago, it was about 4 days late which I wasn't too worried about because I had skipped the last 3 but I still have my period and I've been taking the active pill for 7 days now. Should I be worried? Or is it just because I skipped those 3 periods and got my last one late? 

Thanks in advance :)