So scared... Any advice please!!

Candice • I have an amazing 4yr old daughter, who was a rainbow baby! We are now expecting a rainbow baby, another princess!
When I went in for u/s at 6 weeks and baby's heart rate was 94 bpm. It seemed slow to me but they told me that was normal. But I just went in for my 8 week appt on Tuesday and my doctor said the heart rate still seems a little slow, and the baby looks small so he is predicting a miscarriage but that it's still a 50/50 chance right now. It is so scary to me, I have had 3 previous miscarriages and am so scared for it to happen again. But none of my miscarriages were this far along. My latest I was 7 weeks. I don't even know what to expect. Has anyone else had this problem, if so please let me know the outcome! I have no spotting, no cramps, no sign of a miscarriage. I still get ocassional nausea, cravings, fatigue. I just can't imagine going in and seeing no heartbeat after I have seen my baby alive with a beating heart!! So scared... Any advice please!!