Please tell me, I'm 6 weeks and 6 days pregnant. Today was my first ul…

Please tell me, I'm 6 weeks and 6 days pregnant. Today was my first ultrasound, the baby wasn't seen, they only said that the uterus became bigger and scared me with an ectopic pregnancy but then seeing my tears they said it might not be visible at such a small term, in fact, not even in the uterus, I'm scared, I don't know what to do, is it really not visible at 6 weeks?