20 week old erratic sleep

Dominic is 20 wks and mainly breastfed; he has formula occassionally when I'm at work a couple of times a week (he won't take expressed milk unless it's a couple of hours old or less). He wasn't premature but had a difficult birth and weighs about 16lb. He found day time sleep difficult from 10-16 weeks but has got better since we introduced some techniques, such as "shh, shh pat" in his cot, etc. He still doesn't have a regular nap pattern. We try to give him three naps a day, though he is very willfull and often refuses to go down even when he's tired.

From 8-13 weeks, he fed twice a night and woke up almost the same time for each feed; about 2.30am and 5.30am. Since then, his night sleeping has been really erratic; over Christmas & New Year, he still fed twice a night but slept well and woke up at about 8am; later than normal. Then for the first 3 weeks of January, he started waking much more often; 4 or 5 times a night. I always assumed he's need feeding but sometimes he would take very little milk and fall asleep in minutes. I wondered whether he was actually hungry. Other times, he would shout, chatter or cry and disturb our nights a lot.

I was sleeping about 4 or 5 hours a night and getting very tired, then suddenly the problem seemed to right itself; amazingly, we had 5 straight nights when he only woke for one feed. Then, two weeks ago, just as suddenly, he regressed again, and now wakes 4/5 times a night. He usually seems hungry and feeds for about 20 minutes at a time but often doesn't want to go back to sleep. I put him in his cot, which is next to our bed, but he chatters and gurgles for up to half an hour. I leave him to it because I don't want him to expect me to pick him up, although he keeps both me and my husband awake. Evenutually, he gets upset and I pick him up to comfort him and then try to get him to sleep again. Sometimes it works, sometimes it doesn't. Regardless, he is usually awake again within an hour.

I also leave him for a few minutes when he wakes in case he isn't really hungry, to give him the chance to self-settle but he never does. He doesn't wake up crying but is very noisy and gets more upset the longer I leave him.

Until recently, I have fed him just before putting him down, though he is usually awake when I put him in his cot. The last few nights, I have fed him downstairs, then got him ready for bed in the dark upstairs and put him down when awake. He is able to go to sleep on his own.

He goes to bed at about 8.15pm, wakes at about 11.30pm, 1.30am, 3.30am, 5.30am and 6.30am. We usually are up as a family by 7.30am. He is really resisting going back to sleep when he has woken; even if he has fed well so I feel like we are all just napping all night. I sometimes bring him into bed with me at 5.30am because I'm so tired, but I don't think he's waking to come into bed with me. He doesn't come into bed with me when he's sleeping well.

Dominic is our first child, I have just started him on a little bit of baby rice; I'm hoping this might help him to sleep longe; and doesn't appear to be teething. He has a bit of a cough at the minute but other than that is really well and happy.

Because Dominic's sleep patterns (or lack of them!) are so erratic, I am finding it difficult to establish the cause to the problems and therefore to know what to do about it. I expect that he will continue to need night feeds for a while yet, though would like to give up breast feeding at 6 months; again, I'm hoping that solids and formula milk will help him sleep better as I will be working 4 days a week from April (at the minute, Dominic goes to nursery for a few hours a week and is happy and content there).

We are thinking of putting Dominic in his own room and feeding him at set times but I'm not sure this won't make things even worse. Sorry for the enormous post! I really hope you can give me some advice as I am getting more and more exhausted!