Sakit pinggang awal pregnancy mmg common, tapi sebab baru 9 minggu I'd suggest check with your doc just to be safe, especially since it's persistent and affecting your movements, better to rule out anything kecil-kecil sebelum jadi besar kan. A few of my mum friends had similar aches early on and turned out hormones je (progesterone loosen ligaments) tapi ada jugak yang ada other causes, so jangan self-diagnose lah. In the meantime try sitting with proper support, jangan tunduk suddenly, dan maybe try gentle stretching or prenatal exercises kalau doc approve, takut apa, just confirm with your gynae first!