Young paw paw trees need shade to start off well for the first couple or few years, after all it is noted as an understory tree in a forest.
To achieve that when I first planted 2 starts of the tree, I grew the quite large multi branched sunflower 'Kong' next to the transplanted tree starts. Shade provided.They (sunflower) self seeded and were there for the second and third year as well. No fruit till year 7, if I recall correctly.
Are you aware that once established they (Paw paws) will aggressively attempt to establish a colony?
Floweri)ng Paw Paw tree 6 days ago.