hCG not doubling :( 7w0d

Hi! Question for all you hCG gurus out there.

I have a feeling I know the answer is bad, but I want to hear from experienced peeps.

hCG on May 26th: 9653 at 6w4d

hCG on May 29th: 11764 at 7weeks

Will this pregnancy be viable? I have my first ultrasound in a week.

Anyone who has experience with serial hCG tests please reply! I’m so nervous with 3 previous losses :(

UPDATE #1: I went for an ultrasound and they found an empty sac around 5w6d (was supposed to be 7w1d). I go for hCG twice this week and then another u/s on Friday. I’ll update at the end of the week but I’m not feeling too hopeful. All my pregnancy symptoms are more or less gone... :(