Sleepless nights are so horrible I can remember that time so well! It sounds like you are doing a really good job and leaving her in her room only going in to check on her is great you are letting her know that you are still here and she will feel safe. I did the dream feed at 10 as well and that helped a little but he still woke a few times after. Does she sleep much during the day? How long are her sleeps and is there a routine of what time she goes down? I think if she is waking up for the dream feed it has become a routine for her and she expects it but does not need it. If you still want to five it to her go in at 9 or 9.30pm and give it to her then to change the routine and see if she sleeps through the normal 10pm feed. Are her waking times during the night at different times or around the same time? Babies easily get into a rountine of waking at the same time especially if you go into their room when they do. One trick that worked for me is my ds woke at 1.00 am every morning so I would go into his room around an hour before or even 20 mins before and wake him just until he stirred then walk out. What this does is disturbs their routine and breaks their pattern. He stirred at 1.00 the first night but didn't cry and the second night he slept through. You usually need to do this for at least three nights.
I got a lot of great ideas from a book by Tracy Hogg ( The baby whisperer). It actually has great problems and solutions for the growth spurt stages and many other sleep problems that occur and its about max $20.
I really hope that you get a full night rest soon! You sound like a really great mum Olivia is very lucky!