Family Law Custody and child support.

I live in Location: Colorado USA. I know I need to seek a lawyer. Looking for initial advise of this issue. I am in a partnership as a step parent but not married. As our child of shared custody is getting older I need help. As this child gets bigger he hates me more and more but I support them almost 100%. As a non custodial parent what rights do I have?

Me and my partner share finances. My partner does not make a lot of money in their part time work. The other Parent does not make regular child suppot payments. They got a deal when it was set up they did not have to have a direnct wage farnishment payment. In the past they would not pay monthly but then make some of it up with tax maoney and make a lump sum payment. This year it has not happend. My partner is reluctant to move forward with any legal processs. What Can I do? What rights do I have as a main contributor to this child’s well being?