pregnant without hcg

Has anyone here had experience with getting pregnant without an hCG shot? After several negative urine and blood tests, I’m having an ultrasound next week to see if I’m pregnant (so exciting!). I’ve been having quite a few symptoms, including a missed period (for a few months now) and a growing belly. But is it possible to be pregnant if all the tests are negative? With my other two pregnancies, I usually got a pretty positive test result pretty quickly.