Modifying child support/sep agreement

I’d like to have my child support payments as well as my separateion agreement modified and am curious how to go about doing so. Per our agreement, my ex wife is able to claim both children on her taxes. Last year I had the children 15 more overnights for the year than she did. This has been true for other years, but I only started to document last year. I would like to have our agreement changed so that I may claim one since they are indeed in my home half the year.
Also, in our parenting agreement it states I am to provide before and after school care as well as school vacation care since I work from home. This is something I fought for since I did not want my children going to a babysitter while I am able to provide their car. My ex wife has never stayed home with either of our children when they were sick, nor has she provided any care for them during school holidays, vacations, teacher work days etc… I looked into what Track Out camps and before and after school costs would be and it is very significant. My question is, can I have my child support payments reduced since I am providing all of the child care? Our agreement has been in effect for over 3 years. Could it be considered time to reassess?
Thank you in advance.

You can file a motion to modify child custody or support regardless of what your separation agreement says. The court won’t modify any of the other terms of the agreement unless the agreement specifically says those terms are modifiable.