KimmyF - not sure if it will help you but we found our DD had food intolerances. We had our GP put DD at 6mths on phenergun to sedate her which I refused to do, it wasn't until she was 15mth when a friend suggested we do an elimination diet. Her sleeping improved dramatically within 3-5days

Before

bedtime routine
Dinner, bath, bottle/BF, story, rocking
She would be very hard to settle, she seemed hypo and her arms and legs were always moving.
DD would wake 15-20 min later and then every 5-15min until midnight when she would sleep for about 2-3hrs wake again BF, sleep for 2-3 hrs wake for BF and this would continue until she was awake around 8-9am

She would nap for 20-40 mins 2-3 times a day it was draining and I was at my wits end.

Now on a salcilyate free diet she sleeps from 7:30 until 2-4am when she might wake or 60-70% of the time she sleeps through until 6:30

Check out the website fedup for more info on food intollerances. Not sure if it relates to your situation but it made a huge difference to us, I had no idea food could effect sleep so much.