questions about my practice

I have been practicing insight meditation daily now for over 6 years. I have learnt the Mahasi Sayadaw tradition. I focus on my abdomen rising and falling and notice when my attention goes to something else which seems to be mostly thoughts and then I gently bring it back. When my attention goes to a sensation I watch the sensation for a while until it is no longer holding attention then I bring it back to the breath. After 6 years of doing this I can't say that I have had profound insight into the true nature of reality etc. Most of the time I just feel really bored and doubtful that sitting all this time is actually changing anything. My concentration is only marginally better. I understand Dukha, Anicca and Anatta but its more from reading about it than sitting. I sit for an hour in the morning and 45 mins at night. Im not sure whats going on but just feels something is missing. I read about and hear people talking about the profound changes they experience and how their lives are filled with peace and joy from practicing so I wonder where Im going wrong? As far as Metta practice goes I am told that at first it may feel contrived but if you keep going it begins to work but I have to say that after all these years not much has changed on that front either. It seems that the effort and energy I apply massively out weighs the benefits. So I'm confused about this.