3 miscarriages now pregnant, but scared.

Hey everyone I'm hoping someone rise can relate. I've had 3 miscarriages over the years. I do have one beautiful little girl but she is from my first marriage. My husband desperately wants a child of his own. We've gotten pregnant two times before but I can not get past 6 weeks.  I am two days late for my period have sore breast and was very tired so I took a test. It's positive! I know I should be very happy but every time I go to the bathroom I'm waiting to see red. I've always wanted another child and know stress was probably a factor before but how do I relax?? I hate having anxiety every time I use the bathroom. Dreading the worst. Any suggestions I'd really appreciate it. I'm hoping this is my rainbow baby. Thanks ladies