I am 4 days late for my period, took a hpt the first day, negative. Blood work negative. Still no period, could I be pregnant?

Yes. Yes, you could be pregnant and it's just too early for pregnancy test to be positive. Or, your menses is a little irregular this month and you'll get your period soon. What are your periods usually like? Are the regular? Just wait another week or so. .... You will either have a period or a positive pregnancy test.