9 week old development

My DD is 9 weeks old...has had weight gain issues since 3 weeks. Is only now 8lb 9oz!

Anywho- I am inquiring as to how other 9 week olds are progressing with physical development...I fear that she is behind possibly due to her small size. So first I was wondering if your 9 week olds are able to track objects well? And how much head control they have?

My LO is not tracking object across her vision line well. Maybe on a rare occasion. She can focus on faces and objects but not always consistently- seems to depend on her attention span and mood. She is able to keep her head upright in a sitting position but bobbles still. During tummy time, she can pick her head up to turn side to side but doesn't hold it up and only enough to turn her head.

Let me know what you think and how yours are doing with these milestones!l