my son is 4.5 months old and we have only just seen an improvement in naps and sleeping after realising i was probably keeping him up too long. he has never been a 3 hour clockwork baby and needs more feeds as the day goes on. his rough times are
7 feed
8/8.30 sleep
10 wake
11ish feed
12 sleep
2ish on a good day wake!
feed on waking
4pm ish feed
try to have another short sleep here if he is tired or woke early from lunch time nap
5pm ish drink of water if poss. or feed
play bath etc
6.15 ish feed
6.30 /7 bed
I don't know many people who can get feeds/naps etc all to synchronise to a 3 hour routine, I don't stress about it, i roughly know what is happening now, especially in the morning, it is usually late afternoon that goes pear-shaped! I hope you manage to find what works for you,it is nice to feel a bit more in control and have time to do some things now, my husband even commented that the house looks really tidy just now!