Freaking out. Please help

Hey guys I just had a miscarrige 2 weeks ago, my dr gave said it was okay if I wanted to have sex again but me and my fiancé wanted to wait to try for another baby until I had my first period, well things didn't go planned and he "relieved" his self in me last night, twice. I'm really scared that I might fall pregnant again because they say you are most fertile after a miscarrage, I'm not ready to be pregnant this soon after a miscarrige, I'm still grieving from it. I really regret having sex this soon. Please help..