My parents are fighting?

My parents (who never got married) are fighting a lot. My mom has custody of me, but I want to live with my dad. She keeps ruining the weekends that I have with my dad(I get to see my dad every other weekend and for 3hours on Wednesdays) by griping at him about money. I hate it. I tell her to stop. I threaten to move in with my dad, but she doesn't care. She keeps ruining mine and my dad's weekends, and I always end up crying. She gripes about him not following the court orders by bringing me home at 9 pm on Sunday instead of 6 pm, but she doesn't follow the orders (she's supposed to pick me up from my dad's house but since they live an hour apart she refuses so my dad spends $30 on gas every Wednesday, and every other weekend) she keeps calling him a shitty father even though he's a better parent than she is.

1. How does my dad get court ordered custody?

2. How do I convince my mom to follow court orders?

3. How do I tell my mom lightly that I want to live with my dad?