Struggling to believe I’m pregnant

I don’t know why, but I am still in just disbelief that I am pregnant. I’m 29, I’ve never been pregnant before, never even a false positive, but for some reason, I just still have doubts that I’m actually pregnant. I’ve only had one dr appt so far (when I was 8 weeks) and one ultrasound (9weeks) and now I’m at 14 wks 3days and I can’t help but think maybe I’m not actually pregnant and I’m just getting fat. Has this happened to anyone before? I thought that seeing the heartbeat would make it real for me but it hasn’t. Maybe when I see an actual outline of a baby?? Help?!