Pregnant after a miscarriage, feeling unsure

Hey everyone!
I'm really nervous and just need to get this off my chest.
I already have 2 kids, aged 3 and 22 months. My pregnancies went very well, never had any problems. But then I was pregnant with the 3rd. I did a test, went to the doctor and she said I was pregnant but very early, even though I was already 2 weeks late, so I had to get another blood test to see if the hCG was rising enough. That was the case, so I was reassured, probably a late ovulation. At 8 weeks I had to have an ultrasound and it came as a shock, I was soooo nauseous and my belly was already bigger (even though I was only 8 weeks, the gyn said it's because of 3 kids one after another and then everything stretches faster) I felt really super pregnant! On the ultrasound, nothing, absolutely nothing to see! I had amniotic fluid, a placenta, everything that was needed, my uterus was the size of 8 weeks but there was no fetus in it and my body just carried on as if nothing. I've never felt so bad and even like a failure, I mean, pregnant with nothing, how terrible can it be! I had to have everything removed and then I felt better little by little but I still really want a 3rd child. And the gyn said you've already shown twice that it works, it will work again.
Now pregnant again, I'm super insecure. This time the hCG level was normal but still, I called for an appointment with the gyn but she can only see me when I'm 8 weeks, not earlier because otherwise they won't see the heart yet. (I'm about 5.5 weeks now). But waiting more than 2 weeks is really super long when you're this insecure! So he said I need to get blood drawn again tomorrow to see if it has risen enough. But yeah, that was also the case last time. So I just keep anxiously waiting!

Thanks for letting me share my story!