I am now 7 days late on my period, I took a pregnancy test but it came back negative. I have cramps like I'm supposed to have a period but I don't. I get tired more easily and have tender breasts. Also my nipples are darker than what they usually are. Should I get a blood test or am I just not pregnant?

Honestly, there is no possible way we can tell you if you're pregnant. Those symptoms can also be related to PMS

I would suggest waiting at least one more week - if your period does not come, test again at that point. If the test is positive or negative, at two weeks late, that's be a good time to call your doctor and get their opinion