I think YOU need one weekend a month for yourself, especially if you're working 5 days a week.
"I want as much stability in her life as we can provide too. I need one weekend a month for myself, especially since I'm working 5 days a week. You'll need to provide for your child care needs for our daughter on the one weekend a month that you have her if you have other plans."
Good luck with whatever you decide.
"Always go straight forward, and if you meet the devil, cut him in two and go between the pieces." - William Sturgis, clipper ship captain, 1830's.