How can i get my 6 month old to sleep longer at night?

my daughter is just 6 months old and will not sleep 4 longer than an hour at night without waking, during the day she has a few naps but only for about 15-20Min'ss these naps continue till about 11 pm thats when she will settle and sleep for the 1-1.5 hours she has rice cereal in the morning and fruit for lunch and 4-5 bottles during the day even with a bath everynight still wont sleep longer only if she is in my bed and right next to me will she sleep abit longer??