Getting my 6 month old to take longer naps and sleep better at night?

My 6 month old takes about a hour and half nap at 11:00am and then it all depends for the second nap. Sometimes 30 mins and then an hour to 2 hours later another 30 mins then 9:00 pm every night he is off to bed and goes right to sleep then wakes about 12:00am for feeding and then back up between 3 and 4am for another feeding.Then I will put him back in his crib but every morning around 5 wants to lay with me and we will sleep to around 7:30 to 8:30 in the morning.He is such a happy baby. Not fussy or anything but I know he would be even more happy with more rest full naps and sleep. (also would I ).He eats break fest lunch and dinner everyday and formula between feedings when going down for nap or when awakes. I am doing what the doctor told me to do getting him on a routine and everything.But nothing. We are not even going out and about for the day. We may go out side for fresh air but no long shopping days. I am open for help I am trying all different things with him. I have read to let him CIO and then I heard not to let him. If anyone could help that would be great.