Hi Diana
Your LO is now moving into the time when they need a little less sleep than a new born.
http://babywhispererforums.com/index.php?topic=85134.015 - 18 hrs of sleep in a 24hr period is a rough guide to their needs.
Your LO appears to be getting between 14.5 (based on 11hr night, 2 x 45 min naps and 1 2hr nap) and 15.5 hrs (based on 11hr night and 1 x 1.5hr, 1x 2.5hr, 1 x 45min naps). So, there is room for more nap sleep and ideally you'd have the nap sleep more evenly spread (3 x 1.5hr plus a CN of 45min for example). You're still doing pretty well though!
It could be that his sleep has gone a bit off based on his changing needs or the growth spurt.
It could be that a small tweak to your routine might help even things up.
How about trying a slightly shorter second A time after the first nap? Limiting it to 1hr rather than 1hr 15. This may reduce the long nap slightly, allowing him to wake for his 2.30 feed and stay awake for the next full A. The third nap could then extend based on him having had a slightly shorter second nap because the third nap appears UT.
As a separate point, the first nap of 45 min looks UT but you already have him over his ideal A time there so I wouldn't really want to push that just yet. I'm half wondering if he is keeping that nap short knowing that he is going to get such a long luxurious second nap - it's just a hunch.
Meanwhile, if you are in need of some sleep yourself, may I suggest during the first nap you do only what is vital in terms of laundry and bottle sterilising if needed, leave everything else. During the second nap as soon as he has gone off to sleep go directly to your bed, lay there for the full 2 hrs even if you don't sleep. Laying still in a dark room with your eyes closed can do wonders for your sense of well being, and if you do manage to sleep then even better. Doing this for a couple of days can really make a difference to how you feel. xx