Feeling down!

hi guys I'm currently 14 weeks and 4 days and don't feel pregnant anymore. this is my second pregnancy so I know I had this limbo last time then my bump popped overnight at 17 weeks. I just expected with twins and second pregnancy Id have a proper bump. I just feel fat(ter) than before but can't feel a hard bump. I'm scared I'll go to 16 week appointment and there won't be heartbeats. I had a mmc years ago and although it was at 10 weeks I can't help worry.