I cannot think what else it can be. It might be better to wait until it has mature burrs. https://vicflora.rbg.vic.gov.au/flora/taxon/d4aa44f6-cc9d-4870-8450-d3ab7aee3dc2#&gid=1&pid=1 This plant is very atypical, with very short flower stalks, small leaves, and few petals. Vicflora says about this species has 15-60 petals.