Is it normal to see only the gestational sac at 5 weeks 3 days pregnant?

Yes. Often only a sac can be seen at early part of 5 weeks. A transvaginal ultrasound at 6 weeks should visualize a fetal pole.
It may be normal. Your dates may be off, or the machine used to scan your pelvis may not be good enough to see a yolk sac and an embryonic pole. For more details, get a transvaginal ultrasound and repeat in a week. Take Folic Acid 1-5 mg daily and best of luck!