Aduh sayang, I understand la your worry especially dengan history gugur sebelum ni, memang scary jugak! Cramps at 7 weeks boleh normal (implantation and stretching), tapi dengan back pain and fatigue, plus history mo, please just see your doctor to get checked rather than wait until 8 weeks, okay? The heartbeat might be there already at your stage, and kalau doctor confirm semua okay, boleh rest your mind lah. A few of my mum friends in similar situation went early for reassurance scan and honestly, melihat heartbeat tu buat semua worry go away, totally worth the peace of mind! Take care of yourself, and jangan stress sangat because stress pun boleh bikin cramping worse. Rooting for you!