are you paying attention to things that can make it hard for you to have lucid dreams? are you getting enough sleep? are you smoking too much weed? do you have a nutritious diet? are you getting enough exercise? not staying healthy can make it harder to have lucid dreams and smoking too much weed can make it too hard to remember them. otherwise, if you're keeping a dream journal and doing reality checks(making sure you're acctually considering that you might be in a dream, its easy to to be just do your reality checks with little attention or consideration and then they aren't going to do anything) daily, i don't know if there is really anything that i can tell you other than keep at it. it might just take 3, 4, 5 months.
there is one thing that may help, which is body awareness meditation. it helped me become aware of a lack of physical body when i was asleep and reminds me that i have a body sitting in bed while i am asleep. here is a good video http://www.youtube.com/watch?v=obYJRmgrqOU. at the end he has you noticed sensations in all of your body. i did that for about an hour a day a long time ago and that was how i learned to lucid dream very easily.
edit: also it would be helpful if you would describe your daily habits and what lucid dreaming methods you are using.