Hcg increasing, not doubling

Alissa • Dear son born 5/7/18. Three angel babies. Dear son born 8/27/20 and pregnant with our first girl and last baby Pittsburgh PA-C

My hcg at 4 weeks 1 day was only 61.

I had some light brown spotting which has resolved.

I repeated labs 48 hours at 4w3d and it only increased to 105.

I have had two prior miscarriages and I'm terrified.

Is this pregnancy nonviable??