Where’s my period?😭😭😭

So Back in January, I got my period from the 6th to the 9th. (my period has always been 3/4 days long) then my period stopped. i thought i was pregnant after a month & a half of being late. took test, after test, after test. pretty much had every symptom. nauseous, always peeing, tender boobs, suuuper tired. I haven’t got my period since. All the test are negative. I went to the doctors for a urine test, took at least 20 at home test, and even did a blood test with my doctor. At this point the not knowing is what’s scaring me. Why haven’t I got my period? Should I go get an ultrasound? Could I be pregnant?