Low hcg at 4 weeks???

J

I had an ectopic pregnancy in January which resulted in losing my left tube. My cycles never quite went back to normal but did start to decline: normal was 28, after ep 40, 36, 32. I got a positive hpt at 9pm on Monday which was day 27 of my cycle. I’ve taken a test every morning and the line is getting darker. I had blood drawn on weds morning and the dr said the level was very low (157) but it may be because I’m very early. Not sure at all what day I conceived as 3 dif apps had 3 dif fertile windows. I’ve had symptoms since mid day Monday (nausea, back pain, fatigue, serious heartburn) and I’m just so nervous I could have a miscarriage. I don’t think I can handle one after the trauma of the ep. has anyone else had low hcg at 4 weeks that went on to a successful pregnancy? I’m having more blood drawn tomorrow but won’t get results until Monday. My LMC was 5/15.