Cyst Or Fibroid

Can one twin hide behind the other? 13 weeks measuring 18, feels like twins.?
I’m 13 weeks pregnant but measuring 18 weeks. Dr saw one baby & thought she might have seen another one. Sent me out for another u/s, tech said only one baby, but didn’t really look. Was out in a little over 5 minutes. I’ve been suspecting twins for a while. I know twins can lay side by side (left & right) and top & bottom. But can/will they lay front & back? Could it be possible that I’m carrying twins? No cyst or fibroid, why else am I measuring 5 weeks bigger?? 3rd pregnancy & both the others were VERY normal!
I would let the doctor know that you feel you didn’t get a very good ultrasound appt. Maybe ask for another one. Has he heard two heartbeats? I haven’t heard them lying front and back. Maybe they were moving around. I would ask for another ultrasound. Good luck!
fibroid cyst uterus