I'm 12 weeks pregnant yesterday, I went for an ultrasound scan, the do…

I'm 12 weeks pregnant yesterday, I went for an ultrasound scan, the doctor saw my baby at 6 weeks then told me to come back in 4 weeks and at 10 weeks he said he couldn't see the baby but there was a heartbeat... now at 12 weeks I feel heavy in my lower abdomen, my nipples are severely hurting me, I have no appetite and I'm weak.