Alhamdulillah, jangan risau, ini actually common situation! At 5 weeks, the hCG hormone might still be quite low, so UPT boleh jadi negative even though scan dah nampak the gestational sac; some of us went through the same thing and it's honestly quite stressful but totally normal. Doctor won't salah on the scan, they can see the sac clearly on ultrasound even when urine test masih tak sensitive enough, so you're definitely pregnant! A few of my mum friends experienced this and their repeat scan 3 weeks later pun confirm everything was progressing perfectly. Just try to relax and take care of yourself, the nausea and weird cravings are spot on for 5 weeks, so your body's doing its thing okay.