I had 8 eggs with Clomid (clomiphene) but pregnant with one baby? Can I still be pregnant with twins. I did my ultrasaund at 6 weeks

Enjoy your baby. The uterus is really made to carry one infant. If you have had problems within fertility your best chances to carry a baby to term are to have just one baby. A mistake is always possible but it should be relatively easy to pick up more than one heartbeat.