15 is rough. I can envision your nightmare. On one hand you want her to have time with her dad esp. if they have a good relationship; but on the other hand you being the primary parent are taking on all of the expenses and stress of raising a teenage daughter! My advice is you gotta stand your ground with your ex on sharing the parenting responsibilities. If the 2 of you are able to communicate then make a list of what you want and think is fair to ask of him. I.e. Visits are parenting time first fun time second. If scheduling allows, he should share in doing homework with her or taking her to appts/ drive her to and from school, activities and what not... If there is time afterwards then they can do something fun. As far as financial responsibilities go, if he's got the money to take her to the movies or out to eat or buy her stuff then he has the money to pay child support! Basic needs have to come before wants! If he is spending on things she needs i.e. School clothes, lesson costs, school supplies etc then I would accept less child support but if he is only spending money to make himself "fun dad" then make note of this and bring it to court. Also depending on the custody/ visitation agreements you can always file a motion to structure visit expectations.
Sometimes you just gotta be firm. Keep your head up Leomama! It sounds like you are a wonderful parent.