help. period was due 1/16/18, Neg tests

Cheyenne • Cheyenne Rose✨

I've taken dollar tree tests, and 3 first response tests all negative. for about two weeks now I've had lower back pain/cramps. also kinda dry down there, & creamy cm. should I just get a blood test? my friend insists i can get negative tests and still be pregnant. my cycles are always normal.