Give yourself a pat on the back mate, my DS is 6 1/2 months and we are still working on self settling so with a 3 month old I think you are doing fab.

The 45 min sleeps during the day are a killer. How is bub when he wakes? Happy and ready to play or sleepy and still obviously tired. If bub is happy then don't try to force sleep but if bub is still giving tired signs I would try to help him resettle. Impossible sometimes I know but worth a try.

1 to 1.5 hours of awake time is plenty for his age, it might even be too much. Usually one hour (including the feed) is as much as they can handle before they get tired. All babies are different though so your bub might be more 'awake' than others. It may mean that he is having two short sleeps in the 3 hour cycle.

The best way I can tell if DS was tired at 3 months was his eyes. He got really red eyebrows and would just stare and wouldn't fix gaze on me. As he has gotten older he is more obvious and now rubs his eyes, yawns but in the early days it took a lot of just watching him to figure out his signs.

As I said you are doing a fab job.

HTH
Spring