S.L.
My son is also 9 weeks old. He sleeps about 5-6 hours during the day, usually 2 or 3 naps. I am nursing and my son was eating every 2-3 hours day and night until about a week ago. He is now eating every 2-3 hours during the day and every 3-4 hours at night. He seems to be a good sleeper, but his appetite prevents him from sleeping in longer stretches at night (he is still less than 10 lbs). Based on what I have been told and what I have read, just follow you baby's lead at this age, if you are at home and can be flexible. And watch for signs of fatigue like yawning or lack of interest in playing as signals that he may be tired, and try to put him down for a nap.