Uy, delayed period after restarting pills is pretty common talaga, the hormones can take a bit to regulate, lalo na kung may gap ka between stopping and starting ulit! A few of us mums have experienced this and it usually settles within a week or two, pero since you're already 4 days late at may withdrawal pa, better safe than sorry, maybe grab a PT from Mercury or Watsons just to be sure, para ma-ease ang mind mo, tapos follow up with your OB if kailangan pa, okay?