Worried

So I finally got my first pregnancy, and I went into the doctors on Wednesday my hcg was at 49 and they tried an ultrasound but couldnt see nothing but a cyst my obgyn says it’s probably just early not to worry but still a chance of ectopic so they had me go in Friday to do labs to check my hcg levels they went up to 144 from 49 in two days. But he said still a chance till my next appointment when I should be farther along on Dec 13. I’m about 3 weeks I think and should be about 6 then. I’m so worried since and help up but keep wondering any tips or signs I can look for that might be give me a sign if it’s may be bad or good news then? I hate to think negative but can’t help but having it in the back of my mind.