Aiyo, jangan risau okay! 6 weeks tu memang pelik2 sikit, cramps hilang is actually normal sebab uterus expanding, and the extreme hunger + fatigue tu hormones punye kerja (hCG naik tinggi, body working hard to build the placenta). Second pregnancy memang lain sikit dari first, so tak payah compare. Baby still ada, jangan worry, if baby tak okay, usually you'd see heavier bleeding atau severe cramping (bukan just mild cramps yang dah hilang ni).
Lesu dan lapar tu legit pregnancy symptoms at 6 weeks, some mums dalam my mum group mentioned they were napping twice a day and eating every 45 minutes Just make sure you're eating proper meals with protein, not just snacking, so your energy sustains a bit longer.
But since you're overthinking (totally get it, second pregnancy nerves is real!), best to confirm with your scan soon, that's when you'll see baby's heartbeat and feel so much better. In the meantime, rest when you can and don't compare to first pregnancy, every one is different. Hang in there!