period late for a week?

Melinda • First little bug due May 13,2018 ❤️

My period was due a week ago, and I still haven't had any PMS or any signs that it's on its way. I last took a pregnancy test probably 3 or 4 days ago and there was no second line. I'm not under any stress, so I'm not sure what the deal is. I just wish it would show so we can try again! my question is, is this normal? and also, has anyone been pregnant but not gotten a positive pregnancy test even a few days after your missed period?