7weeks and 3days pregnant but no heartbeat

Posible ba tlga na 7weeks preggy nako pero di parin nakikita ung heartbeat ng baby? Nagpaultrasound kase ako TRANVAGINAL ultrasound.. pero sabi ng dra ko hndi oa daw makita ang heartbeat kaya pinababalik ako after 2weeks... dpat ba ko magworry? Help naman po mommies...thank you