Suggestion foDivorce Agreement

we almost reach the agreement for divorce. I can get the sole custody for our child on the condition some items in agreement are unfair in some sense (like i will give her some money and i like to supprt the child by myself). When I consulted with laywer, they said the court will not step in the agreement after we make it. BUT no one will stop her to go to court to adjust/change/modify the agreement in the future (like after 4-5 year) and who knows the decree in court at that time? so should I believe her to go forward to do it ? you know , otherwise, we may go to court and spend money and time on this issue now. and even the court like to be joint custody, in fact I spend most of time to take care of the child. thanks for suggestions.