I have a 11 month old daughter. I have jumped through a ton of hoops to get the visitation that I have now. This includes domestic abuse charges that were dropped, threats by my x to call CPS, supervised visits, having to evict my roomates, and a million other things. In our last court date my X used the argument that our daughter was not ready emotionally and developmentally for more time with her father. Currently I have tuesdays and thursdays from 5-9 and alternating weekends from 10-4. I am frustrated because I want overnights. My whole family lives 75 miles away and these short visits make it impossible for me to bring her down there. Any thoughts on how to argue that my daughter is developmentally ready for more time with her dad.
You need to formulate your argument from a "best interest of the child" perspective.
You and the mother can argue back and forth about whether the child is "ready", but it really won't get you anywhere in court. The court will tend to lean towards keeping the status quo arrangements, unless there is good reason to modify it.
I suggest you make a motion to increase your custodial time to include overnights and also for a custody evaluation to assess the stability and caretaking abilities of each parent. Often, if a parent is obsessed with making allegations about the other parent, it may indicate some mental health issues in one of the parents. But it's up to a custody evaluator to conclude that, not you.
Build and argue your case appropriately. As I don't have too many details about your case, I'll leave it to you to do the research as to relevant issues to argue. Look at my Recommended Books
Before filing, make reasonable efforts to work out a new schedule with your ex. Keep copies of emails or letters you send her, so you can demonstrate in court that you're litigating as a last resort (i.e., "In the past 3 months, I've made 8 attempts to resolve these issues with the mother for the sake of our child, and she refused all such attempts").