Has anybody ever gotten pregnant right after a miscarriage?

i had a miscarriage aug 1st started felling funny last friday went to my doc and IM PREGNANT!! =) she said it was 100 fine to try right after bleeding stopped but i am so scared ill have the same result :( has anbody gone through this... according to my doc i am 4 weeks preggo which means i got preggo within days of the miscrriage...