My HCG is low :(

Amber

First day of last period: April 8, 2021

Positive opk: April 24, 2021

Likely Ovulated: April 25, 2021

Last day I had sex was April 25, 2021

Faint Positive pregnancy test: May 6, 2021 (11 dpo) was negative the day prior.

May 7th- 33 (12dpo)

May 11th- 318 (16dpo)

June 3rd - 4669

Had ultrasound 3 days ago and they only saw a gestational sac measuring just under 6 weeks. Ive been spotting brown for a few days to. Am I likely to have a miscarriage given the number is so low? :(