Baby Sleep

How long is your baby sleeping so far? We had a pretty good schedule down but as of yesterday I feel my 16 week old is sleeping way too much. Woke up at about 9 am on Valentine's day then slept from about 4:30pm-10pm. He woke up, ate, then slept from about 10:30pm-7ish this morning. He went to sleep at about 5:45pm today and it's now almost 11:30pm and he still has not woken up. He's moving around a lot but no actual waking up. Anyone else going through this? He has 8oz every 2 and a half to 3 hours when he is up. It's definitely scaring me a bit and sticking to the "they'll wake up if they're hungry" line is getting harder to do.