procedure in WA state to get a parenting plan filed with the court

parenting plan: i had a kid with my girlfriend then we split up.. the kid is 2 now and i support them. i pay for the bills and rent and she has a part time job that pays for food and her gas.. but she is constantly jerking me around with my kid so I wanted to get a parenting plan to stop her from doing this but I have been told that I will be paying more then I am already paying now for her (bills plus rent plus child spport) is this true or will the money I'm giving her for rent and bills count as child support? - Is this your question? Add additional information