Low HCG. Awaiting 2nd levels.

On January 16th I got a positive on the family Dollar band tests. I was only 6 months post c section. I had my period in December on the 15th and my cycle changed to 30 days just recently due to the nexplanon implant problem I had. Well I should've ovulated on the 29th of December and I had sex that day. I also had sex on the 6th of January. I don't know exactly when I ovulated due to the whole cycle change. Well I started spotting pinkish brown then it went to brown with a bit of pink. I went to the hospital in case of etopic. They ran my blood and my levels came back at 100. Doctor said no point in doing a ultrasound because of my levels. I should've been 5 weeks 3 days but I could've also been 4 weeks 2 days if I ovulated later. Is that a low level? I'm waiting for my other draw to come back on Monday but it's really hard. I'm terrified I'm having another miscarriage. Is 100 low? Should I be worried. Took another test and the line is some light but noticeable.