I have jiont custody and my daughters momhas kept my daughter from me for the ast 2 and a half years.?

I am supossed to have my little girl 3days o one week and 4 days of the next and so far I have seen my daughter only three times for a total of about 18 hours in 2 and a half years.Her mother signed her rights to her oldest son over to her mother and it seems she is takeing her hurt out on me. I am broke and can,t afford alawyer andI have court in 3 weeksfor child support but have a copy of the custody pappers that say I,m not to pay child support. what should I do?