Sweetie its ok to be cautious about it all. I know I was in the same position as you. What helped me get through was reminding myself that that it was in the hands of nature and really there was nothing I could do about the outcome but be as healthy in mind and body as I could and in my case keep taking P4 (for FET). You have given your body the best chance to create an embryo, implant and now grow. M/Cs are mostly because an embryo isn't viable for some reason, there is nothing you can do to change the outcome now. I'm not sure if this will help you but its ok to say you are scared of hoping but I hope as the tests continue and the weeks go on you will grow more confident in your baby and body and allow yourself to hope and care for this little one.
Big hugs xx