I'm 4 weeks late, have taken several HPTs all came back negative (including a blood test taking on my 5th and 20th days late). Have lower back spasms, sore nipples, nausea here and there. I am also extremely bloated. Please help.

About all you can do is see what happens when your next period would be due... sometimes a period will be skipped for no obvious reason. If you miss two in a row, check back with your doctor. They will likely repeat the blood test and do an ultrasound as well.