Morning after pill problem?

i took the morning after pill two months ago and had my period normally the next month, but this month it has been 2weeks late (i researched it and it said it's normal for it to throw off your cycle) , i regularly do pregnancy tests and have all been negative, i also want to start Yasmin so i don't fall pregnant but can't because of this, is it fine to start it now because i need to regulate my period again since it got thrown off from that pill?