is there something i can do about his baby mama?

so my husband and i have a 1 year old and he has a 2 year old from a previous relationship. we have been paying child support and all of his medical dental and vision. we usually get him 2 weeks out of the month. when child suplort was established we didnt get him at all though we only had visitation. slowly she wlhas wanted us to take him more and more. but its gotten so bad that for the past 2 months she has barely had him. last month she only had him for 12 days. he just went back to her house 10 days ago and she wants us to come get him again because she wants to go out new years. now keep in mind. for us to go get him it is a 6 hour drive total. we pay her 600 a month and cover all medical, dental, and vision. she pays nothing. im really getting frusterated that she is getting all of this money when hes barely with her...... what do i do? we cant afford a lawyer. we are struggling financially. also she has no job. never has