Well...I'm thinking the doc might have meant in four weeks generally to start again, possibly not exactly four weeks. I believe most pills are either monday or sunday starters and you should always read the directions on the pack to be sure. That could be the cause of your missing your period, plus whenever you start the pill after a long absence, your body needs time to readjust itself. I wouldnt' worry overmuch, but if you are concerned ask your doc. I would suggest stopping what you have taken and start a new pack on the sunday after your period, but im not a doc. Hope that helps!!