Spotting and 6 weeks pregnant

So I went to the ER on Monday night due to some pink spotting. They went ahead and did an ultrasound and said they saw a gestational sac with no yolk sac or fetal pole. They explained that I was measuring 5 weeks and it was probably too early. They took my blood and my HCG was 2555. Fast forward to this whole week and I’m still continuing to spot but with some brown discharge and some red blood. My HCG on Wednesday was 3273 and then on Friday it was 3830.

They said my numbers are doubling but was good they were going up.

But the main thing I’m concerned is that I had a different nurse from the clinic call that day and said to expect my numbers to hit 0 and miscarry.

What do you guys think, has anybody experienced something like this?