It sounds to me like your lo is staying up too long and therefore getting overstimulated, which will always make it hard for them to settle into a GOOD rest whether in a buggy or bed, hence the 45 minute to an hour nap.
Is it necessary that you leave at 10-11 everyday(is it everyday?) If I were you I would feed him at 6:30 and have him back down for a nap, no later than 8:30. 2.5 hours is a really long time for a baby his age to stay awake, you are probably thinking that he isn't tired but I would bet that if you stopped long enough to let him settle down then you would see that he is in fact tired and needs to sleep.
I have been told many times on these boards that sleep begets sleep....it couldn't be more true. the better rested he is during the day, the better rested he will become at night, and hopefully that will increase his waking time to 7, then you could have him back to bed by 7pm completing a 12 hour day. I would really try not to let him stay up so long at least at the first morning nap and then if you need to you can try stretching the second nap time maybe to 2.5 hours (however i doubt that will fly)
my 9 month old still takes 3 naps....not so normal I know but she needs that last catnap to rest peacefully at night, anyhow she can really only go about 2 hours for an awake time if I want her to get a really good nap in.
HTH.... Don't give up after a few days, at your lo age this is going to take a little bit more work that it would have if you had started from thr beginning, don't give up! :wink:
Angie