Pregnant?

Hi! I’m 4 days late. My fiancé and I have been trying for two months and I don’t want to get him excited when I don’t know for sure. I took a pregnancy test first thing this morning and it came back negative. Could I still be pregnant? Has this happened to anyone else and when did you test positive or know for sure you were not pregnant? I’m 22 and I’ve had my period since I was 9. I’ve never been late, even when extremely stressed it has been like clockwork! However, I do have a thyroid issue and had a miscarriage three months ago, both of which affect fertility according to my doctor. Thanks in advance everyone!!!