Can I start new hard drive set up again?/time machine info missing!

Hi, hoping for some guidance as I think I've made a mistake with my new hard drive set up, and now my time machine hasn't transferred everything over as I've folders missing!

My hard drive packed up & a new 10.6 was installed on my Macbook Pro. Previously running on 10.5.8 which was backed up to time machine 3 week ago. I switched on and went through the 'set up assistant' but when asked 'Would you like to inherit (or reuse) the backup?' I think I chose 'Don't backup now' because I thought I could do my time machine later! I now know I have chosen the hard route!!

Then I tried the 'migrate assistant' - it took 1.5hrs - desktop has screen shots etc as before but I couldn't access thing like 'my pictures' in bridge etc. The dock has LR, PS, Bridge etc as before too. Then I deleted the new admin set up (so I had only my old admin.) I restarted - no change. I then tried 'migration assistant' again but transfered only 'Other files and folders' because when all ticked there wasn't enough room (-81gb)

Now I can go into LR catalog it only has 2 folders (instead of more than 20), and in Bridge I have files & folders, but on accessing them I get 'Items could not be found. It may of been moved or renamed.'

I've looked into erase & install - but I don't have the disc. Maybe I should go back to the shop who installed 10.6? Can I start again so I can transfer from time machine in the set up?

Any advise on how I can get my info back would be greatly appreciated!

Thanks, Heather