Spotting and baby measuring 5 days behind

Hi ladies.. so I got a scare a couple of days ago when I spotted for the first time in this pregnancy. Spotted again last night, and got an early ultrasound today. I have a history of a missed miscarriage and I'm already on progesterone vaginal gel since I got my BFP.

Spotting is gone now, nothing since last night, and even when it did occur, it was only a little bit and nothing on the liner I had put in, only if I inserted my finger I got few brown mucusy drops on it. Now it's gone.

But at the ultrasound, baby measured 4 +6 weeks, whereas I should be 5+4weeks today. That's what concerns me, because I know when I ovulated and it shouldn't be measuring behind. My OB explained that it can still happen and each baby grows at it's own pace and it may not always be such a accurate calculation, but Due to spotting, my OB termed it as threatened miscarriage, despite all other parameters of gestational and yolk sacs being normal and a fetal pole was seen as well.

To be safe I was given HCG injection and more progesterone and also baby Aspirin.

I guess what I'm looking for is success stories of women who have been in a similar position.. my next ultrasound is not until 2 weeks later, and that's a long long time to live in continuous fear of miscarrying.. any hope you can give is appreciated and much needed..

Thanks in advance!

PS please let me know if I should post this on any other group so that it will reach more people? Thankyou!